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Outlines  of 


Experimental  Physiology 


ii 


IDA    H.    HYDE,   Ph.  D. 

Professor  of  Physiology  of  the 
University  of  Kansas 


I.AWRENCE,  KANSAS 

1905 


C?A-«?M  4^U^C>^^&iJXji.^\ 


affi- 
le fi 


COPYRIGHT. 
1905. 
By  Ida  H.  Hyde. 


preface 


*  *  it 

This  pamphlet  contains  the  directions  for  the  laboratory  work  required 
of  the  medical  students  in  the  Department  of  Physiology  of  the  University 
of  Kansas. 

While  man}'  of  the  experiments  are  original,  the  author  has  also  freely 
used  the  work  of  others  where  it  seemed  best  suited  for  the  special  subjects 
of  investigation.  For  these  hearty  acknowledgments  are  extended  to 
the  authors. 

Lawrence,  Kansas,  1905. 


Table  of  Contents 

Page 

Aconite,  Effect 44 

Accommodation 86 

Amoeboid  Movements 10 

Anode  and  Cathode  Poles   73 

A  stig-matism 84 

Blood,  General  Directions 18 

Blood,  Globulicidal  Action 17 

Blood,   Laking-     17 

Blood  Microscopic  Study  of 12 

Blood  Pressure 47 

Blood  Opacity - .    17 

Blood  Reaction II 

Blood,  Spectroscopic  Study  of 30 

Blood,  Transfusion  on  Pressure     49 

Blood,  Pigment  Test 30 

Blind-spot  Mapped     89 

Carbonic  Acid  and  Oxygen  in  Air 59 

Cardio  Pneumatogram 59 

Capillary  Electrometer 63 

Carbon  Monoxide  Test 31 

Cardiac  Nerves  . . , 38 

Carotid  Pulse x 41 

Circulation  Time 50 

Circulation  Scheme 32 

Chromatic  Aberration 85 

Circulation  in  Frog's  Web 16 

Ciliary  Motion . .  36 

Conjugate  Foci 82 

Contraction  of  Human  Muscles '. 78 

Conductivity  Changes '75 

Constant  Current  on  Muscles 70 

Complementary  Colors 92 

Coagulation 16 

Comparison  of  Make  and  Break 70 

Constant  Current  on  Irritability 74 

Constant  Current  on  Excitability    74 

Color  Vision  Test 91 

Construction  of  Lense  Images 83 

Curare  Effect 47 

Current  Variations  by  Rheostat 63 

Demarcation  in  Muscle 77 

Diffusion 87 

Differences  of  Potential  in  Muscle 77 

Digitaline  on  Heart 43 

Drug's  Action  on  Heart 42 

Electrotonus 73 

Electro  Magnetic  Induction 66 


Page 

Electro-physiolog-ical  Apparatus 60 

Estimation  of  Ked  Corpuscles 19 

Estimation  of  White  Corpuscles   21 

Eye  as  a  Camera 88 

Exclusion  of  Make  and  Break   70 

Focal  Distance  Estimated    82 

Frog's  Brain 79 

Galvanometer   62 

Galvanis'  Experiment 68 

Gradual  Changes  in  Stimuli   .      .  72 

Haematolog3'  12 

Haemaglobin  in  Blood    24 

Haemorrhage  on  Pressure 50 

Hardy's  Experiment  on  Colloids   35 

Hearing    92 

Heart  Action 39 

Heart  Sounds 41 

Heart  Transfusion  of  Solutions 44 

Human  Muscle  Curves 72 

Hypermetropia 85 

Identical  Points    87 

Induction  Currents 65 

Inductorium 66 

Inhibition  of  Heart 43 

Irritability  and  Conductiviy  of  Nerves 75 

Isotonic  Solutions   23 

Isometric  and  Isotonic  Curves   72 

Keys  or  Switches 62 

Kymograph 37 

Laboratory  Work  Directions 9 

Laboratory  Book  Criticisms 9 

Lack  of  Oxygen  and  KCn 36 

Larjnx .... 93 

Law  of  Muscle  Contraction 76 

Liquif action 15 

Lines  of  Force 65 

Liquifaction  by  Irritants    16 

Lung  Capacitj' 55 

Macula  Lutla 87 

Milammeter 63 

Morphine  on  Heart ^. 43 

Muscle  Fatigue — Work 71 

Muscle  Reaction    , 69 

Muscle  Twitchings  . 69 

Myopia 84 

Near  and  Far  Point- 87 

Negative  After  Image 91 

Nerve  Muscle  Preparation 39 

Nerve  Stimuli 68 

Osmosis 13 


Page 

Osmotic  Pressure 14 

Ophthalmoscope 89 

Perimetry 88 

Physostigma 44 

Phag-ocy  tosis 11 

Pithing  a  Frog 39 

Plasmol^'sis    15 

Polar  Stimulation  of  Heart     . 73 

Positive  After  Images 91 

Previous  Stimuli 71 

Precipitin  Test 31 

Pressure  Pulse 41 

Pulse  Volume 42 

Purposive  Character  of  Reflex 80 

Purkinji  Sanson  Figures 88 

Purkinji  Sanson  Images 83 

Radial  Pulse   42 

Reflection  from  Concave  Mirrors 81 

Refraction  by  Convex  Lenses 82 

Refraction  by  Concave  Lenses 83 

Refraction  by  Segments  of  Lenses 84 

Reflex  in  Man 8i 

Reflex  Inhibition 80 

Reflex  Action  of  the  Spinal  Cord 79 

Reflex  Time 80 

Reaction  Time 81 

Respiratory  Movements 54 

Respiratory  Pressure 56 

Respiratory  Mechanics  of 60 

Respiratory  Chemistry  of .  .  . .    60 

Rheostat  in  Series 64 

Rheostat  in  Parallel 64 

Sciatic  Action  on  Heart 41 

Scheiner's  Experiment 86 

Semipermeable  Membranes 14 

Specific  Gravity  of  Blood 24 

Skin  as  a  Sense  Organ 92 

Stethogoniometer     , 58 

Strychnine  Action ...  46 

Suprarenal  on  Heart 51 

Suprarenal  on  Blood  Pressure 44 

Summation  of  Stimuli 71 

Supplies .* 7 

Surface  Tension 10 

Systolic  Phase 41 

Sympathetic  Nerve 38 

Sympathetic  on  Heart 40 

Taste .  93 

Thoracometer  Records 57 

Valves  of  the  Heart 31 

Veratrine  Effect 47 

Voltmeter 62 

Volume  of  Corpuscles  and  Plasma 22 

Vagus  Action  on  the  Heart 40 


student's  Supplies. 


1.  A  set  of  dissecting  instruments,  one  small  scissors,  one  small  forceps, 

a  metal  seeker,  and  a  medium  sized  surgeon's  needle. 

2.  Four  camel's  hair  brushes. 

3.  Note  book  containing  heavy  drawing  paper  and  note  paper  7^  by  9^, 

cover  8  by  10.      (No.  4.) 

4.  A  small  cbservation  note  book. 

5.  A  padlock  with  two  keys. 

6.  Two  towels. 

7.  Slides  and  cover  glasses. 

8.  Two  pipettes. 

g.      A  tube  of  paste. 

10.  India  ink  and  a  fine  pen. 

11.  A  spool  of  waxed  linen  thread. 

12.  A  spool  of  white  silk  and  a  paper  of  pins. 

13.  The  Physiological  Laboratory  Note-book. 

14.  Students   using    more   than    the    average   number   of  animals,  will   be 

charged  ten  cents  for  each   additional   frog   and  twenty-live  cents  for 
each  tortoise. 

15.  The    cost    of  cleaning,    repairing,    or    replacing   articles    which    have 

become  damaged  will  be  charged  to  the  students  to  whom  they  were 
issued. 


Directions  for   Laboratory  Note  Books. 


1.  --Use 'pen  and  ink  for  writing  all  notes.      Number   each  page   of  notes 

in  the  upper  right  hand  corner  and  write  on  one  side  only. 

2.  Place  all  drawings  and  explanations  of  the  same  on  the  left  pages  on 

heav}'  paper;  th^e  observations  and  conclusions  on  the  right.  Number 
the  plates  in  the  upper  left  hand  corner  with  Roman  numerals. 

3.  Illustrate  rather  than  explain   in  writing.      The   different  parts  of  the 

drawings  are  to  be  labeled  with  small  letters  in  definite  order.  These 
letters  are  to  be  explained  on  the  same  page.  The  heading  of  the 
drawing  is  to  be  placed  above  it. 

4.  Place  the  drawings  near  the  center  of  the  sheet,  allowing  for   a  wide 

margin.  Never  copy  a  drawing  from  a  book.  Put  only  such  draw 
ings  on  a  page  that  relate  to  the  same  subject. 

5.  Arrange  the  notes  of  an  experiment  as  follows:     Head,   number  and 

date  each  experiment  conspicuously. 

6.  State  the  object  of  the  experiment.      Describe  the  method. 

7.  Arrange  the  observations  in  accordance  with  the  order  of  the  directions. 

8.  Whenever  possible,  state  5'our  conclusions  as  a  separate  note. 

9.  Seek  the  laws  or  applications  underlying  each  experiment. 
10..    Work  for  your  own  results.      Doing  is  better  than  seeing. 

I.*--:  .^'  Keep  an  index  of  notes  and  one  of  plates  in  the  front  part  of  the  book. 
12.      Keep  a  correction  sheet  at  the  back  of  the  book  for  all  criticisms. 


Outlines  of  Experimental  Physiology 


LABORATORY  WORK. 

1.  Laboratory  books  must  be  in  Friday  before  six. 

2.  Credit  is  not  given   for  work  not  in  on  time. 

3.  The  work  must  be  illustrated  in  ink  or  crayon;  diagrams  should  be  employed 
whenever  possible.  Time  should  not  be  spent  in  needlessly  detailed  drawings,  make 
all  the  statements  as  concise  and  brief  as  possible. 

4.  Laboratory  periods  are  of  three  and  four  hours'  length.  Less  time  is  not 
credited.  Absence  from  a  laboratory  period  means  that  the  period  is  not  credited 
and  must  be  made  good  before  the  material  for  the  work  has  been  removed.  Three 
absences  from  recitation  and  two  from  laboratory'  periods  during  one  term  require  a 
special  examination  at  the  end  of  the  term. 

5.  The  apparatus  is  divided  into  general  and  private  apparatus.  For  the  for- 
mer, two  students  are  together  held  responsible  and  for  the  latter,  each  student  is 
held  personally  responsible.  The  cost  of  all  broken  or  damaged  apparatus  is  de- 
ducted from  student's  breakage  fee.  Apparatus  left  outside  of  the  lockers  is  collect- 
ed by  the  assistants.  Laboratory  cleanliness  and  neatness  are  considered  in 
making  up  the  final  grade  of  the  students. 

6.  Students  are  urged  to  select  their  comrades  for  themselves.  The  work  should 
be  arranged  so  that  one  day  the  preparation  of  the  frog  or  other  material  shall  fall 
to  one  student,  while  the  arrangement  of  the  apparatus  falls  to  the  other;  the  next 
day,  these  duties  are  exchanged. 


NOTE-BOOK  CRITICISMS. 

1.  At  the  close  of  each  week's  work,  a  list  is  made  of  all  the  work  required  in 
the  note-book  for  that  week.  This  is  placed  on  the  direction  file  by  the  instructor, 
and  is  to  be  used  by  the  student  as  a  guide  in  writing  his  notes  and  to  the  instructor 
in  making  corrections. 

2.  Any  required  work  not  in  the  books  even  in  pencil,  is  marked  missing  when 
the  books  are  corrected.  Notes  or  illustrations  marked  missing  should  be  added  by 
the  time  the  books  are  again  handed  in  for  correction. 

3.  An}-  notes  or  illustrations  still  in  pencil  at  a  time  when  they  should  be  in 
ink  and  completed,  are  marked  "not  complete."  These  should  be  completed  before 
the  books  are  again  handed  in  for  correction,  and  a  statement  made  where  the  cor- 
rection is  to  be  found. 

4.  The  corrections,  "missing"  and  "not  complete"  will  always  be  found  on 
the  correction  sheet.  Criticisms  are  sometimes  made,  however,  on  the  notes  or 
drawings  themselves.  These  are  always  made  in  pencil  so  that  they  may  be  easily 
erased,  and  the  notes  or  drawing  is  marked  "criticised,"  on  the  correction  sheet. 
Criticisms  should  not  be  erased  bj'  the  students  until  they  are  marked  O.  K.  on  the 
correction  sheet. 

5.  No  erasures  or  marks  of  any  kind  except  the  statement  under  3  are  to  be 
made  on  the  correction  sheet.  When  any  criticism  has  been  corrected  satisfactorily, 
the  instructor  will  place  the  mark  "O.  K."  after  it  on  the  correction  sheet. 

6.  The  instructors  will  always  be  glad  to  assist  the  students  in  any  waj-  pos- 
sible in  their  work  in  the  laboratory  or  in  writing  notes  on  their  work.  Thej-  will 
also  be  glad  to  explain  any  criticisms  not  understood  by  the  student. 


10  Outlines  of  Experimental  Physiology 


PHENOMENA  RELATED  TO  THE  STUDY  OF  BLOOD  AND  CIRCULATION. 

Spontaneity  is  the  power  apparently  possessed  by  living  things  by  virtue  of 
which  they  carrj"^  on  activities  independent  oi  external  stimuli  or  changes  in  their 
environment.  Some  or  all  so-called  spontaneous  actions  may  be  referred  to  responses 
to  stimuli. 

Manifestations  of  life  as  exhibited  in  the  reactions  of  leucocytes,  amoeba,  infu- 
soria and  other  forms  of  life,  are  due  to  physical  and  chemical  phenomena  or  stim- 
uli. A  knowledge  of  these,  it  Ls  believed,  will  aid  us  to  interpret  more  correctly  the 
complex  functions  exhibited  in  higher  forms  of  life.  As  an  introduction  to  the  study 
of  blood,  we  begin,  therefore,  with  experiments  involving  special  physico-chemical 
laws  that  pertain  to  the  reaction  of  protoplasm. 

Expt.  I.     (A)     Amoeboid  Movements  and  Reactions. 

(1).  Place  a  drop  of  water  containing  amoeba  on  a  slide  and  examine  under  the 
high  power,  (a).  Study  the  movements  of  the  amoeba  and  of  the  ectosarc  and  en- 
dosarc  (b),  reactions  to  light,  mechanical  stimulations  and  food  particles,  (c),  note  the 
effect  of  placing  a  heated  needle  point  in  advance  of  the  amoeba  on  the  slide  under 
low  power. 

(2).  Study  the  currents  in  a  drop  of  fluid  due  to  changes  in  surface  tension. 
Mix  some  India  ink  or  lamp-black  with  clove  oil, — place  a  drop  of  the  oil  on  a  slide 
in  a  mixture  of  two  parts  of  glycerine  -to  one  part  of  95  per  cent  alcohol.  Support 
the  cover  slip  with  a  hair  or  glass  fibre.  It  has  been  assumed  by  some  authors  that 
amoeboid  movements  are  due  to  changes  in  surface  tension.     Are  they  alike? 

Literature. — Jennings,  Study  of  Lower  Organisms,  1904;  Davenport,  Experi- 
mental morphology;  Verworn,  General  Physiology. 

(3).  Phj'sical  Imitation  of  Reaction  to  Stimuli.  Place  a  drop  of  castor  oil  1-10 
mm.  in  diameter  in  alcohol  under  the  supported  cover  slip.  Bring  a  capillary  tube 
containing  5  per  cent.  KOH  or  chloroform  under  the  cover  near  the  drop.  The  KOH 
diffuses  out  against  the  drop,  lowers  the  surface  tension,  and  the  drop  reacts  by 
entering  the  tube. 

(B)     Experiments  in  Surface  Tension. 

(1)  Make  a  wire  ring  and  to  this  attach  a  loop  of  thread  (see  model).  Dip  this 
ring  into  a  solution  of  soap  so  that  a  film  of  soap  is  stretched  across  the  ring.  Have 
the  thread-loop  float  on  this  film.  Notice  the  shape  of  the  loop.  Puncture  the  film 
in  the  loop  by  means  of  a  hot  wire.     Effect?     Explain. 

(2).  (a).  Place  a  thin  rubber  band  on  the  surface  of  the  water.  Notice  its 
shape.  Dip  a  pencil  or  wire  into  alcohol  and  then  into  the  water  within  the  rubber 
band.  Notice  the  effect,  (b).  Place  several  bits  of  cork  near  each  other  on  the 
surface  of  the  water  and  then  bring  a  drop  of  alcohol  on  a  wire  into  the  midst  of  the 
particles.  Explain,  (c).  Cover  a  clean  glass  plate  with  a  thin  layer  of  water. 
Dip  a  glass  rod  in  alcohol  and  bring  it  near  the  center  of  the  wet  surface.  Explain 
the  resulting  phenomenon. 

(3).  In  a  watch  crystal,  place  about  10  c.c.  of  5  per  cent.  H2SP4.  In  this  place 
a  small  drop  of  mercury  and  near  the  Hg  a  tiny  piece  potassium  bichromate, 
(b).  Hold  a  nail  very  near  to  the  Hg.  The  drop  of  Hg  will  change  shape  (describe 
and  give  reason)  and  will  pulsate  rhythmically.  Place  a  piece  of  K2Cr20T  very 
near  the  Hg  and  notice  the  progressive  movement  of  the  Hg.  K2Cr2  07  oxidizes  the 
Hg  when  it  touches  it  and  lowers  the  surface  tension  at  the  point  of  contact.  Fe 
carries  plus  charges;  it  robs  the  Hg  of  some  of  the  negative  charges  which  have 


Outlines  of  Experimental  Physiology  11 

electrostatically  formed  a  double  layer  around  the  Hg.     What  is  the  result?    Hg 
ions  resist  gravit}'  by  cohesion. 

(4).  Draw  a  needle  between  thumb  and  linger  to  cover  it  with  a  thin  coat  of  oil. 
Hold  the  needle  parallel  to  the  surface  of  the  water  and  gently  place  the  needle  on 
the  surface.  Notice  that  the  needle  floats.  Observe  the  surface  of  the  water  around 
the  needle.  Now  clear  the  needle  in  Na2C03  solution.  Does  the  needle  float? 
Explain  this  phenomenon  fully. 

(5).  Place  3  or  4  drops  of  water  in  a  watch  crystal  and  on  the  water  place  a 
drop  of  castor  oil.  Watch  behavior  of  the  oil.  Make  this  same  experiment  with 
cedar  oil.     Why  do  these  two  oils  behave  diff^erently? 

(6).  In  a  watch  glass  place  4  c.c.  of  )4  per  cent.  NagCOs  solution  and  add  a 
drop  of  oli%e  oil.  Place  the  watch  glass  on  a  black  surface.  Study  the  spreading 
of  the  soap  and  oil  and  the  formation  of  processes.  Repeat  until  thoroughly  familiar 
with  the  phenomena.     What  becomes  of  these  processes  finally?     Why? 

(7).  Place  a  drop  of  olive  oil  on  a  slide  and  near  it  place  a  drop  of  Nag  CO  2  so- 
lution. Carefullj- bring  the  two  drops  together  and  observe  the  action.  Notice  the 
vortex  movements  in  the  oil  drop.     Repeat  several  times. 

(8).  Place  4  c.c.  of  water  in  a  watch  glass  and  carefully  place  a  drop  of  olive 
oil  on  the  surface  of  the  water.  About  1  cm.  from  the  oil  drop,  place  a  piece  of  the 
NagCOa  crystal.     Where  does  the  spreading  take  place?     Why? 

(9).  Place  a  few  bits  of  camphor  gum  on  warm  water.  Explain  the  phenomena. 
(10).  Blow  a  soap  bubble  without  detaching  it  from  the  pipe.  Leave  the  stem 
open  and  notice  the  bubble.  Does  it  retain  its  first  volume?  Explain.  Fill  a 
pipette  to  a  given  point  with  water.  Slowly  expel  and  count  the  drops.  Repeat, 
filling  the  pipette  to  the  same  point  with  alcohol.  Is  there  anj-  difference  in  the  size 
of  the  drops?     Explain. 

(11).  Fill  a  long  glass  tube  drawn  out  to  a  fine  capillary  with  water.  Does  the 
water  issue  from  the  capillary  as  a  steady  stream?  Explain  rhj'thmic  phenomena. 
(12).  Secure  an  air  bubble  under  a  piece  of  glass  in  a  dish  of  water.  Arrange 
a  bent  tube  drawn  into  a  capillary  at  one  end,  the  other  end  dipping  into  a  bottle  of 
alcohol.  So  arrange  the  tube  that  a  fine  stream  of  alcohol  strikes  the  center  of  the 
bubble.  How  many  times  does  the  bubble  beat  rhj'thmically  and  what  forces  pro- 
duce the  rhjthm? 

Literature. — Loeb,  Phys.  of  the  Brain,  p.  21. 

Expt.  II.     Phagoc3'tosis. 

(1).  Inject  powdered  carmin  suspended  in  m  |  8  NaCl  solution  into  some  grass- 
hoppers and  into  the  lymph  sack  of  a  frog.  Examine  the  blood  after  15,  30,  and  60 
ninutes. 

The  power  of  taking  up  foreign  or  solid  particles  has  been  thought  due  to  local 
iquefaction  of  the  white  blood  corpuscles. 

Literature. — Hekton,  Pathology  143;  Loeb,  Studies  of  General  Physiology. 

Expt.  III.     Reaction  of  Fresh  Blood. 

(zi.)  Obtain  blood  as  directed  under  General  Directions  on  page  18.  Allow  a 
Irop  of  violet-red  litmus  tincture  to  soak  into  a  porous  claj'  plate,  then  place  on  the 
pot  a  drop  of  blood  and  wash  it  off  at  once.     What  is  the  color  reaction? 

(b).  The  reaction  maj*  also  be  shown  with  red  litmus  paper  that  has  been 
Qoistened  in  sodium  sulphate  or  concentrated  magnesium  sulphate.  Place  a  drop 
if  blood  on  the  paper  and  absorb  the  liquid    at  once  with  blotting  paper. 


12  Outlines  of  Experimental  Physiology 


NORMAL  HAEMATOLOGY. 

The  examination  of  the  blood,  like  that  of  the  urine,  gives  a  positive  diagnosis 
in  a  number  of  diseases.     The  examination  of  the  normal  blood  consists  of  an  actual 
study  of  the  bloed  by  use  of  the  microscope  and  the  determination  of  many  of  its 
properties  by  the  use  of  various  instruments.     The  accurate  use  of  the  instruments 
can  be  learned  onlj^  b)'  experience.     While  the  instruments   are  delicate  and  easily 
broken,  j^et  the  technique  of  their  use  is  easily  mastered  by  the  student  if  he  is  care- 
ful, accurate,  and  persevering.     The  technique  once  acquired   can  be   quickly  re- 
gained in  later  years  although  it  may  apparently  be  forgotten  for  the  time  being. 
Speed  in  the  tests  can  be  obtained  only  by  continuous  practice.     Theoretically  all 
these  instruments  are  accurate,  but  because  of  the  minute  quantity  of  blood  used, 
slight  inaccuracies  vpill  be  multiplied  in  the  final  results  and  may  be  large  or  small 
according  to  the  experience    and   carefulness  of  the  observer.     By  knowing  where 
these  errors   are   possible   and   avoiding  them  by  the  best-known  methods,  and  by 
adopting  a  definite  method  of  use  of  each  instrument,   these  inaccuracies  can  be 
largely  eliminated   and  good  comparative  results  obtained.      In  the  use   of  blood 
instruments  the  observer  must  constantly  avoid  manufacturing  results.     There  is 
always  a  tendency  to  read  into  a  test  a  preconceived  result.     This  is  best  governed 
by  control  tests  and  by  repeated  tests.     When  one  can  repeat  a  test  three  or  four  times 
with  the  same  individual's  blood  and  obtain  approximately  the  same  results  he  is 
quite  proficient. 

Reference  Books:  Clinical  Examination  of  the  Blood,  by  Cabot.  Clinical 
Pathology  of  the  Blood,  by  Ewing.  Clinical  Haematology,  by  Da  Costa.  Histology 
of  the  Blood,  by  Ehrlich  and  Lazarus.  Text-book,  on  Physiology,  by  Hall.  Works 
on  Histology  and  Physiology. 

Expt.  IV.  Microscopic  examination  of  blood  fresh  and  stained  is  of  great 
clinical  importance.  In  some  diseases,  it  gives  a  specific  diagnosis  which  could  not 
otherwise  be  gained. 

Study  the  red  and  white  blood  corpuscles  of  man,  frog,  sheep,  or  other  animal. 
Draw  surface  and  side  views. 

Appliances: — Microscope,  eyepiece  micrometer,  white  ground  glass  slides,  cover 
glasses,  Paccini's  Fluid. — HgCl2  1  gram,  NaCl  2 grams,  Glycerine  13  grams.  Dis- 
tilled water  325  grams. 

The  micrometer  is  a  small  piece  of  glass  on  which  there  is  a  scale  marking  off 
equal  spaces.  This  is  placed  on  the  diaphragm  of  the  eyepiece  of  the  microscope 
and  put  in  focus  by  pushing  it  up  or  down  as  needed.  The  scale  is  then  compared 
with  a  stage  micrometer  marked  in  microns,  and  the  value  of  the  eyepiece  scale 
thus  determined. 

Preparation.  Wash  the  cover  glasses  and  slides  with  soap  and  water  and  then 
"thoroughly  rinse  in  clean,  warm  water.  Polish  the  glsses  with  a  clean,  soft  towel. 
When  handling  the  slides  or  cover  glasses,  hold  them  always  by  their  edges  and 
never  touch  a  flat  surface.  Success  in  preparing  fresh  blood  specimens  depends 
largely  upon  the  absolute  cleanliness  of  the  glasses  used.  Before  using  the  glasses 
pass  them  through  the  Bunsen  or  alcohol  flames  six  or  eight  times  while  holding 
them  with  the  fingers,  then  they  will  not  be  broken.  Put  the  glasses  down  in  a 
clean,  safe  place,  with  the  heated  side  up,  as  this  is  the  side  to  be  used. 

Technique.  Obtain  the  blood  as  before,  using  the  second  or  third  drop.  Bring 
one  of  the  previously  heated  cover  glasses  underneath  the  drop  of  blood  and  allow  it 


Outlines  of  Experimental  Physiology  13 

to  jvist  touch  lightly  the  centre  of  the  glass;  then  quickly  place  the  cover  glass,  blood 
side  down,  upon  a  glass  slide.  If  the  glasses  are  clean,  the  blood  fresh  enough, 
and  of  the  right  amount,  the  blood  will  spread  out  into  a  thin  layer,  in  which  the 
corpuscles  lie  on  the  flat  surface  in  a  single  layer.  Around  the  margin  the  cells 
will  be  more  or  less  grouped  together.  Protect  further  with  vaseline  around  the 
edge  of  the  cover.  The  specimen  should  then  be  jilaced  under  the  microscope  and 
studied  at  once. 

(a)  Mix  a  small  drop  of  blood  with  a  small  droj)  of  water;  (6)  another  with  a 
drop  of  Paccini's  Fluid,  placed  on  the  skin,  which  is  then  punctured,  letting  the  blood 
flow  into  the  fluid.  Put  a  drop  of  these  on  a  slide  and  cover  with  a  cover  glass  and 
examine,  (c)  Smear  a  drop  of  blood  on  a  slide  by  drawing  another  slide  over  it. 
cover  one  with  a  glass,  and  {d)  make  another  and  leave  uncovered  and  examine. 

Precautions.  It  is  very  important  that  the  slides  and  cover  glasses  should  be 
kept  perfectly  clean  and  dry.  If  alcohol  is  used  an  alcoholic  residue  is  left  upon  the 
glass  and  often  interferes  with  the  examination.  Touching  a  glass  surface  with  a 
freshly  cleaned  finger  will  leave  enough  f;it  and  dirt  to  prevent  the  blood  spreading. 
The  blood  must  be  transferred  to  the  gL-isses  and  covered  quickly,  or  it  will  partially 
clot  and  prevent  spreading.  The  drop  must  be  large  enough  to  give  a  clean  field  of 
at  least  one-half  inch  in  diameter,  but  it  must  not  be  so  large  that  the  blood  cannot 
spread  out  into  a  thin  film  between  the  glasses.  The  spreading  must  take  place 
entirely  by  capillary  attraction;  pressure  must  never  be  used  to  continue  or  cause 
spreading.  The  glass  must  touch  only  the  tip  of  the  drop  while  obtaining  the  blood; 
if  it  touches  the  ear  the  blood  will  not  spread. 

QUESTIONS— Red  Cell. 

1.  Describe  a  red  cell,  shape,  dimensions,  and  variations? 

2.  What  are  the  maximum  and  minimum  dimensions? 

3.  What  percentage  are  large,  normal  or  small? 

4.  How  are  the  red  cells  arranged? 

5.  What  causes  crenation? 

6.  What  causes  vacuolation? 

7.  How  large  are  blood-platelets? 

8.  What  happens  to  the  red  cells  in  the  presence  of  water? 
•  9.  What  happens  to  the  red  cells  when  drying  in  the  air? 

10.  What  happens  to  the  red  cells  when  spread  by  pressure? 

11.  Of  what  does  a  red  cell  consist? 

12.  Are  red  cells  nucleated? 

White  Cell. 

1.  Describe  a  white  cell,  its  dimensions  and  nucleus? 

2.  Are  there  any  variations  in  the  size  of  a  white  cell? 

3.  What  are  the  percentages  of  the  various  sizes? 

4.  Do  they  float  readily  under  the  cover  glass? 

5.  What  becomes  of  the  white  cell  in  the  presence  of  water  and  while  drying  in 
the  air? 

6     Of  what  does  a  white  cell  consist? 

Semi -Permeable  Membranes  and  Osmosis. 

Expt.  V.     All  substances  in  solution  tend  to  dift'use   from  regions  of  higher  to 
regions  of  lower  concentration.     The  pressure  to  which  this  movement  is  due  is  the 


14  Outlines  of  Experimental  Physiology 


osmotic  pressure;  that  pressure  is  the  same  as  would  be  exerted  by  the  dissolved 
substance  if  it  were  in  the  form  of  a  gas  of  the  same  temperature  and  volume  as  the 
solution.  (Law  of  van't  Ho£f.)  If  solution  and  solvent,  e.  g-  ,  water,  are  separated 
by  a  membrane  which  is  permeable  to  the  solvent,  but  not  to  the  dissolved  substance 
(semi-permeable  membrane),  the  effect  of  the  osmotic  pressure  is  seen  in  an  increase 
in  the  volume  of  the  solution  due  to  the  passage  of  the  solvent  into  it  through  the  mem- 
brane. 

Semi-permeable  membranes  are  of  universal  occurance  in. living  organisms  and 
are  represented  by  the  cell  walls  of  animal  cells  and  the  plasma  membranes  (pri- 
mordial utricles)  of  plant  cells 

(A)  Artificial  Scmi-Permeabic  Membranes. 

(1).  (a).  Using  a  fine  pointed  pipette,  attached  to  a  supported  burette,  introduce 
carefully  a  drop  of  m/5  CUSO4  solution  beneath  the  surf  ace  of  an  m/7  K4Fe  (Cng) 
solution  in  a  watch  glass.  Note  that  the  two  solutions  do  not  mix.  Why?  Note 
size  of  the  CUSO4  drop;  set  aside  and  note  if  its  size  changes  in  the  next  hour  or  so. 
Measure  by  placing  a  paper  scale  under  the  dish. 

(b).  Repeat  using  ^/z  CUSO4.  Set  aside  for  one  hour  and  note  effect, 
(2).  Ascertain  if-  the  semi-permeable  membrane  of  Cuo  Fe  (Cng)  is  permeable 
to  other  substances;  e.  g.,  sugar.  Prepare  a  large  globule  of  the  ^/z  CUSO4  solu- 
tion; then  inject  into  it  with  a  fine  long  nozzled  pipette  an  ^/i  solution  of  cane  sugar. 
If  carefullj'  done,  the  sugar  solution  will  form  a  separate  layer  at  the  bottom  of  the 
globule  next  the  membrane.  Does  the  sugar  solution  flow  out?  What  do  j'ou  con- 
clude? 

(3).  Good  artificial  membranes  are  also  made  as  follows:  Use  a  10  per  cent, 
gelatine  solution  that  has  been  boiled  till  dt  no  longer  gelatinizes  (eight  hours). 
Beneath  the  surface  of  this  solution,  introduce  a  drop  of  a  second  solution  containing 
equal  parts  of  5  per  cent,  tannic  acid  and  m/ cane  sugar.  Note  the  character  of 
the  membrane  formed.  What  is  the  reaction?  Try  tannic  acid  M'ithout  the  sugar. 
Any  difference?  Why?  Note  the  changes  in  the  size  of  the  globules  after  varying 
intervals  of  time.  Also  color  the  tannic  acid  solution  with  Congo  red.  Note  if  the 
color  passes  the  membrane  or  not.  What  do  you  conclude  as  to  the  permeability  of 
the  membrane  ? 

The  osmotic  pressure  of  CuSO 4  is  less  than  that  of  K4Fe  (Cng).  1  per  cent, 
cane  sugar=47  cm.  of  Hg  pressure.  1  per  cent  K2S04=193  cm.  Hg.  1  percent. 
KN0  3=178cm.  Hg. 

(B)  Natural  Semi-Pcrmeabic  Membranes 

(a).  Cut  a  cylinder  of  beet  3x1  cm.  and  wash  in  several  changes  of  water  for  an 
hour.  Then  place  in  a  beaker  and  cover  with  100  c  c.  distilled  water.  At  the  next 
laboratory  period  concentrate  the  100  c.  c.  to  4  c.  c  and  test  for  sugar.  Result? 
(Boil  about  10  min.  with  25  per  cent.  HCI,  then  use  Trommer  or  Fehling's  test). 

(b).  Obtain  a  solution  of  the  beet  pulp  by  cutting  the  cylinder  lengthwise, 
scrape  out  the  pulp  and  grind  in  a  mortar  with  sand  and  100  c.  c  water.  Press 
out  the  liquid  through  cheese  cloth  and  evaporate  to  4  c.  c.  Does  this  solution  give 
the  reaction  for  sugar?    What  are  your  conclusions? 

(4).  Obtain  3  sets  of  osmometers,  three  long  glass  tubes  and  three  pieces  of 
membrane.     Parchment  paper  is  not  a  true  semi-permeable  membrane,  but  approxi- 


Outlines  of  Experimental  Physiology  15 

mates  such  a  membrane.  Soak  the  parchment  paper  in  water,  then  fasten  it  over 
the  osmometers.  Test  by  placing-  it  under  water  and  blowing-  into  it.  Use  rubber 
or  water  proof  cement,  vaseline  and  rosin.  Fill  one  of  the  osmometers  with  an  m  ,^ 
cane  sugar  solution,  a  second  with  an  ^/C  NaCL  solution  and  a  third  with  a  solu- 
tion of  albumen.  To  fill  the  osmometers,  use  a  small  pipette.  Now  attach  to  the 
nipple  of  each  of  the  osmometers  a  long  glass  tube,  b}'  means  of  a  short  piece  of  rub- 
ber tubing;  (or,  better,  with  glass  directly,  using  waterproof  cement).  Support  the 
osmometers  on  j-our  desk  in  a  large  dish  of  distilled  water,  or  in  three  small  dishes 
containing  enough  water  to  just  cover  the  osmometers,  label  and  date  each  After 
24  hours,  note  the  difference  in  the  height  of  the  fluid  in  the  three  tubes,  Explain. 
What  is  osmotic  pressure? 

(5).  Use  an  egg  membrane,  seal  a  capillary  tube  to  a  punctured  side  and  re- 
move the  shell  from  the  other  wider  end,  which  dip  in  water. 

C.   Plasmolysis  of   Plant-Cells  and   Blood  Corpuscles. 

(1).  Mount  some  Spirog3'ra  fllaments  on  a  slide  in  a  drop  of  water  and 
familiarize  yourself  with  the  structure  of  the  cell.  Note  the  spiral  bands  containing- 
chloroph}-!  (chromatophores),  the  nucleus  and  the  thin  laj-er  of  protoplasm  just  in- 
side the  cell  wall.     Sketch.     (Stain  with  carmine  to  bring  out  the  nucleus). 

(2).  Place  a  few  of  the  Spirogyra  filaments  on  a  slide  in  a  drop  of  m/i  cane 
sugar  solution  (by  M  is  denoted  the  Mol  or  gram-molecule-liter  solution),  support 
the  cover  glass  on  bits  of  paper  and  study  the  changes  that  take  place  in  the  cells 
(plasmolj'sis  of  the  cells).  Sketch,  comparing  it  with  its  appearance  before  placing- 
in  the  solution. 

(3)  Repeat,  using  an  ^^A,  ^^./lo,  and  an -^1/20  solution  of  cane  sugar.  Note 
the  effects  produced  in  each  case. 

(4).  Repeat  the  above  experiments,  using  instead  of  cane  sugar  a  10  per  cent, 
solution  of  either  gelatine,  egg  albumen,  or  urea  ^^ /  20-  Why  does  not  this  solution 
acton  the  cells  in  the  same  waj'  as  the  cane  sugar  solution? 

(5).  Repeat  the  above  experiments  on  Vorticella  or  Paramoecium,  using-  sugar 
solutions  of  2M,  ^^/i,  and  "^1/20  strength.  What  strength  of  solution  is  practically 
isotonic  with  the  cell?     Does  plasmolysis  result  with  strong  solutions? 

(6).  Collect  a  small  drop  of  blood  upon  the  slide,  according  to  the  directions  on 
page  18  and  cover  it  with  a  cover  slip.  Note  carefully  the  size,  contour  and  behavior 
of  the  red  blood  corpuscles  for  a  few  minutes.  Prepare  a  second  slide  in  the  same 
way,  only  immediatelj'  after  covering,  permit  a  drop  of  distilled  water  to  flow 
under  one  edge.  Upon  a' third  slide  let  a  drop  of  M  sugar  solution  run  under  the 
coverslip.  Watch  and  compare  the  appearances  of  the  red  corpuscles  in  the  three 
experiments.     Draw.     Explain. 

(7).  Find  the  sugar  solution  which  affects  the  corpuscles  least,  i  e.,  is  isotonic 
with  them, 

Expt.  VI.  (A).  The  corpuscles  develop  the  property  of  adhering  to  the  walls 
of  the  vessels  in  so-called  inflammatory  states  It  may  be  due  to  changes  which 
induce  liquefaction.  The  latter  is  produced  bj'  lack  of  oxygen,  action  of  OH  and  H 
ions  by  replacing  the  insoluble  Ca  by  Na,   Li,   K,   by  certain  drugs  and  by  heat. 

(a).  Place  a  crustacean  (amphipod)  in  a  hanging  drop  in  an  Engelmann  gas 
chamber.  Observe  the  circulation  in  the  leg-s,  note  the  behavior  of  the  corpuscles. 
Pass  hj'drogen  through  the  chamber  until  changes  in  the  circulation  are  noticed ;  now- 
pass  oxygen  through  and  observe  effects,  then  carbon  dioxide  and  note  the  changes. 


16  Outlines  of  Experimental  Physiology 


Revive  with  oxygen.     Note  in  each  case  the   changes   produced  on  the  v? alls  of  the 
vessels  and  in  the  blood. 

(b).  Liquefaction  and  differences  of  osmotic  pressure  of  different  solutions. 
Place  corpuscles,  also  Paramoecia  or  Vorticella,  on  plane  or  cell  slides  under 
covers  supported  by  hairs,  (The  animalcules  are  obtained  by  filtering  the  infusion 
containing  them  through  a  tiny  paper  filter  and  the  apex  of  this  with  the  animal- 
cules in,  is  then  placed  in  a  small  dish  containing  a  little  fresh  water.  From  this 
supply  material,  the  Infusoria  may  either  be  put  on  a  slide  or  in  a  small  watch 
crystal).  Allow  a  drop  of  NaCl  m/jg,  KCl  m/jg,  CaClg  ^/w,  MgClg  t^/iq, 
NaOH  iq/800,  HCl  Di/800to  flow  under  the  coverslips  and  note  changes  in  the  cor- 
puscles or  Infusoria. 

(c).  Repeat,  keeping  the  corpuscles  and  Infusoria  in  the  various  solutions  24 
hours.     Study  the  effects  of  the  chemicals  on  the  protoplasm. 

{d).  Liquefaction  by  heat.  Place  a  slide  with  a  hanging  drop  containing  the 
material  experimented  with  in  (6)  on  the  warm  stage,  heated  to  about  38  =  C,  and 
note  the  effect. 

Microscopic  Study  of  Circulating  Blood  and  Liquefaction  by  Irritants. 
Expt.  VI  (B).  Place  a  small  frog  with  a  bit  of  cotton  moistened  with  a  drop  of 
ether  under  a  tumbler  until  the  frog  is  partially  anaesthetized.  It  must  still  respond 
to  eye  reflex  and  just  attempt  to  turn  over  if  placed  on  its  back.  Lay  it  covered  with 
moist  paper  and  the  bit  of  ether  cotton  at  its  nares  on  the  cork  frog  plate  kept  in  place 
by  the  microscope  clips,  and  pin  either  the  tongue  or  web  over  the  glass  cover.  Tie 
a  thread  to  2d  and  3d  toes,  the  web  between  these,  not  too  tightly  stretched,  is 
pinned  down. 

(a).  Study  with  both  the  high  and  low  power  the  velocity  and  flow  in  the  axis 
and  periphery  of  the  blood  stream  in  arteries,  veins,  and  capillaries.  How  can 
you  distinguish  these? 

ib).  Is  there  a  pulse?  in  which  blood  vessels?  Is  there  a  disappearance  and 
appearance  of  capillaries?  Can  you  detect  white  and  red  corpuscles?  Are  there 
evidences  of  elasticity  and  flexibility?  of  diapedesis  of  corpuscles?  Note  the  width 
of  the  vessels  in  a  special  area  to  compare  with  (2). 

(2).  {a).  Put  a  piece  of  ice  on  the  foot,  and  after  a  few  minutes  note  the  effect 
(a)  on  the  flow  of  blood  and  the  width  of  the  above  noted  vessels. 

(b).  Place  a  bit  of  cotton  heated  with  water  to  about  38=  C  on  the  same  area; 
again  note  the   flow   and  width  of  the  vessels. 

(c).  Put  a  drop  of  NaCl,  8  per  cent  ,  on  the  web;  note  results;  wash  off;  effects? 
(d).     Put  a  drop  of  chloroform  on  a  fresh   area  of  the  web.     Effect?     Wash  off 
thoroughly  with  water. 

(e).  "When  the  circulation  is  about  normal  put  on  a  drop  of  turpentine.  Effect? 
Wash  off  with  water. 

(/).  Place  a  small  drop  of  oil  of  mustard  on  the  web.  Note  effect.  Wash  off 
with  water.  State  your  observations  regarding  the  influence  of  toxic  or  irritating 
substances  upon  the  inflammortj'  state,  the  flow  and  behavior  of  corpuscles? 
Coagulation  and  Fibrin  Ferment. 
Expt.  VII  (a).  Place  a  drop  of  blood  on  a  slide,  expose  it  to  the  air.  Soon  filam- 
ents radiate  from  the  centres,  apparently  blood-platelets.  A  small  aperture  diaphr- 
gam  and  little  light  make  them  plainer.  Their  importance  is,  that  under  certain 
pathological  conditions,  the  fibrin  network  is  much,  increased  and  helps  in  diagnosis. 


Outlines  of  p]xperimental  Physiology  17 


It  is  important,  therefore,   to  be  familiar   with   ordinary  net   work  in  normal  blood. 
Compare  either  with  frog^'s  or  with  fellow  student's  blood. 

Coagulation  of  Normal  Blood. 

The  coagulation  of  normal  blood  is  a  phenomenon  that  lakes  place  quite  constantly 
in  from  three  to  five  minutes.  But  in  disease,  this  time  ma3'  be  prolonged  indefi- 
nitelj'.  The  coagulation  ma}-  be  approximately'  tested  by  taking-  a  large  drop  of 
blood  on  a  warm  slide  and  while  holding  it  in  the  hand,  draw  through  the  drop  a 
needle  or  a  straw  everj'  minute  and  note  when  a  clot  follows  the  straw  out  of  the 
drop.  Wrig-ht's  instrument  for  testing-  coagulation  is  slightly  more  accurate.  Are 
there  any  variations  in  the  time  of  coagulation  among  the  individuals  in  j-our 
section? 

Other  Experiments  on  Coagulation. 

Expt.  VIII.  (a).  Opacity  of  Blood.— Smear  a  little  fresh  blood  on  a  glass  slide 
and  laj'  the  slide  on  some  printed  matter.  It  will  not  be  possible  to  read  it,  be- 
cause the  light  is  reflected  from  the  corpuscles  in  all  directions  and  little  of  it 
passes  through. 

(<?>).  Laking  of  Blood. — Put  a  little  fresh  blood  in  three  test  tubes,  A,  B  and  C. 
Dilute  A  with  an  equal  volume,  B  with  two  volumes  and  C  with  three  volumes  of 
distilled  water  and  repeat  (a).  The  print  can  now  be  read,  probably,  through  a 
laj'er  of  B  and  C,  since  the  haemoglobin  is  dissolved  out  of  the  corpuscles  by  the 
water  and  goes  into  solution,  the  blood  becoming  transparent  or  laked.  That  the 
difference  is  not  due  merel}'  to  dilution,  can  be  shown  by  putting  an  equal  quantity 
of  blood  into  two  test  tubes,  D  and  E,  and  gradually  diluting  D  with  distilled  water 
and  the  other  with  a  0.9  per  cent,  solution  of  NaCl,  but  use  more  of  NaCl  solution 
than  3'ou  do  distilled  water  for  D.  Print  can  now  be  read  through  the  first  (D) 
with  a  smaller  degree  of  dilution  than  through  the  second  (E).  Whj-?  Examine 
the  laked  blood  with  the  microscope  for  the  ghosts,  or  the  shadows  of  the  red  cor- 
puscles. The  addition  of  methylene  blue  will  render  them  somewhat  more  distinct. 
Take  a  drop  of  D  and  E  and  see  the  great  difference  between  the  corpuscles  under 
the  high  power  of  the  microscope.     Conclusion? 

Globulicidal  Action  of  Serum. 

Expt.  IX.  (a).  Make  a  careful  study  of  the  frog's  and  calf's  blood  before 
bringing  them  together.  Note  the  size  with  the  micrometer  scale;  the  form  and  ap- 
pearance of  the  red  and  white  corpuscles. 

{b).  Place  a  small  drop  of  frog's  and  one  of  calf's  blood  on  a  slide  not  quite 
in  contact  with  each  other.  Put  on  a  cover  glass  so  that  the  two  drops  just  touch. 
Examine  at  once  with  high  power.  Note  the  changes  produced  in  the  size,  form 
and  appearance  of  the  frog's  blood  acted  upon  by  the  calf's  serum,  and  the  calf's 
acted  upon  by  the  frog's  serum. 

{c).     What  would  ^-ou  infer  regarding  the  osmotic  pressure  of  the  different  sera? 

(d)  Heat  some  of  the  calf's  serum  to  about  55- C  for  from  a  '4  to  '2  hour  and 
repeat  {b).  What  is  the  result?  What  change  was  produced  in  the  calf's  corpuscles 
after  they  were  heated? 

Literature  — Iminune  Sera,  Wassermann  ^lnd  Boldnar.  Blood  Immunit\',  Nut- 
tall 

(2).     Haemolvsins  and  Agglutins. 


18  Outlines  of  Experimental  Physiology 


GENERAL  DIRECTIONS. 

All  blood  instruments  must  be  perfectly  clean  and  dry  if  the  best  results  are  to 
be  obtained.  The  various  pipettes  are  cleaned  by  the  use  of  hydrog-en  peroxide  and 
distilled  water;  they  are  then  dried  by  the  use  of  alcohol  to  remove  the  vs^ater, 
followed  b}'  ether,  which  will  evaporate  quickly  and  remove  the  alcohol. 

Hydrogen  peroxide  oxidizes  organic  matter;  alcohol  and  ether  coagulates. 

The  cleaning  fluids  (hydrogen  peroxide  and  water)  are  used  by  filling  the 
pipette  and  rolling  it  for  a  few  minutes  between  the  thumb  and  fingers  and  then 
blowing  or  drawing  the  fluid  out. 

In  the  use  of  drj'ing  fluids  (alcohol  and  either)  do  not  blow  the  fluids  out  of  the 
pipettes,  as  the  moisture  of  the  breath  will  defeat  the  object  which  one  is  seeking. 
Having  filled  the  pipette  with  alcohol  or  ether,  draw  it  into  the  rubber  tube,  replace 
it  upon  the  pipette,  then  draw  air  through  the  pipette.  After  using  alcohol  in  this 
way,  followed  by  ether,  one  may  be  assured  that  the  pipette  is  absolutely  dry. 

For  the  student's  work,  secure  the  blood  from  the  lobe  of  the  ear  or  the  side  of 
the  tip  of  the  thiid  finger.  The  ear  is  better,  as  it  contains  fewer  nerves,  gives 
more  blood  and  will  continue  to  bleed  for  a  longer  time.  The  ear  or  finger  should 
be  lightly  washed  with  a  towel  moistened  with  distilled  water,  then  dried  with  the 
towel  to  remove  any  dirt  or  loose  epithelial  cells.  The  needle  used  should  be  a  fair 
sized  glover's  needle.  It  is  a  three-sided  needle,  the  sides  of  which  are  so  ground 
that  each  has  a  fine  saw-edge,  and  will  not  cut  the  tissues  as  a  saddler's  needle  will. 
The  needle  should  be  kept  clean  with  distilled  water  and  hydrogen  peroxide,  and 
sterilized  with  alcohol.     A  lancet  may  be  used  instead  of  a  needle. 

The  puncture  should  be  made  by  holding  the  lobe  of  the  ear  between  the  thumb 
and  finger  and  pricking  lengthwise  of  the  ear  in  its  lowest  part  The  needle  should 
enter  about  one-quarter  of  an  inch,  and  should  be  thrust  in  quickly  while  the  thumb 
and  finger  hold  the  ear,  and  when  withdrawn  it  should  be  given  a  half-turn  and  be 
quickly  removed.  The  first  drop  of  blood  should  always  be  wiped  away  to  moisten 
the  skin  with  blood,  and  also  because  it  clots  quicker  than  the  following  drops. 

The  blood  should  gradually  ooze  out  of  itself  It  should  never  be  forcibly 
squeezed  by  pinching,  as  that  will  give  an  abnormal  specimen;  but  the  ear  may  be 
gently  pressed  an  inch  or  so  above  the  puncture,  to  make  the  blood  flow  more  freely 

To  fill  a  pipette  by  suction,  take  the  lobe  of  the  ear  between  the  thumb  and 
finger  of  the  left  hand,  standing  behind  and  to  the  right  when  using  the  right  ear 
and  in  front  and  to  the  left  when  using  the  left  ear.  Place  the  tip  of  the  pipette 
upon  the  thumb  that  is  behind' the  ear,  hold  the  pipette  with  the  right  hand  near 
its  upper  extremity,  with  the  marks  showing  in  front;  then,  by  turning  the  thumb, 
insert  the  capillary  point  into  the  drop  of  blood  and  do  not  allow  it  to  touch  the  skin 
of  the  ear;  the  column  of  blood  drawn  into  the  capillary  must  be  accurate  and  com- 
plete. It  must  not  remain  short  of  or  go  beyond  the  mark  desired,  and  air  must  not 
be  allowed  to  enter  the  pipette.  If  any  of  these  errors  take  place  the  pipette  must 
be  recleaned,  dried  and  filled  again 

When  properly  filled,  any  blood  adhering  to  its  outer  surface  mu.-^t  be  completely 
removed  before  proceeding  further.  It  is  better  to  have  a  large  drop  of  blood  at  first 
than  to  use  two  or  three  small  drops,  as  there  is  less  liability  of  getting  air  into  the 
capillary  and  of  the  blood  clotting.  Be  sure  to  clean  the  apparatus  before  putting  it 
away. 


Outlines  of  Experimental  Physiology  19 

Expt.  X.  Introduction. — In  health  the  number  of  red  cells  in  the  blood  is  quite 
constant.  The  variations  that  occur  are  quite  small  and  are  due  to  normal  pro- 
cesses. In  the  male  there  are  about  5,000,000  red  cells  in  each  cubic  millimetre.  In 
the  female  there  are  about  4,500,000  cells.  Any  deviation  from  normal  health 
quickly  causes  a  diminution  in  the  number  of  red  cells  In  fact,  simply  unhyf^ienic 
surrounding-s  or  habits  are  sufficient  to  speedily  reduce  the  number  of  red  cells 
without  other  demonstrable  pathological  conditions.  The  life  of  the  red  cell  is 
probably  of  about  two  weeks  duration.  There  are  approximately  in  the  normal 
male's  blood  200,000,000,000  red  cells.  Then  according  to  the  length  of  the  lifetime 
of  the  cells,  about  14,000,000,000  cells  die  and  must  be  disposed  of  each  day.  A  cor. 
responding  number  must  be  manufactured  each  day  in  order  to  keep  the  number 
within  its  normal  limits.  It  will  be  readily  seen  that  such  an  immense  process, 
which  depends  upon  perfect  elimination  as  well  as  assimilation,  can  be  disturbed 
very  easily.  It  is  important  that  this  fact  about  the  blood  be  thoroughlj'  under- 
stood. Even  though  the  phj-sician  may  not  estimate  the  number  of  red  cells  in  every 
case,  yet  he  must  recognize  the  fact  that  every  disturbing  element  in  the  normal  body 
must  disturb  the  number  of  red  cells  contained  therein.  There  are,  then,  two  objects 
to  be  gained  by  actually  counting  the  I'ed  cells  and  estimating  their  number.  First, 
to  gain  a  clear  idea  and  understanding  of  the  number  of  red  cells  in  normal  blood; 
and  second,  to  be  able  readily  and  accuratel}'  to  estimate  the  number  of  red  cells 
per  cubic  millimetre  in  any  given  clinical  case. 

There  are  three  methods  of  estimating  the  number  of  red  cells  per  cubic  milli- 
metre: 

1.  The  Thoma  Haemacytometer.  An  instrument  by  which,  with  accurate 
dilution,  the  corpuscles  may  be  actually  seen  and  counted  in  a  known  space. 

2.  The  Oliver  Haemacytometer.  This  instrument  depends  upon  the  transmis- 
sion of  a  transverse  line  of  light  from  a  candle  through  a  flat  glass  tube.  The  blood 
stops  this  light  until  a  certain  dilution  is  obtained.  The  tube  is  graduated  to  read 
the  number  of  cells  per  cubic  millimeter  of  the  blood  used  according  to  the 
dilution. 

3.  The  Haematocrit.  B}'  this  instrument  is  obtained  the  volume  of  the  cor- 
puscular elements  in  the  blood  by  centrifugation.  From  this  the  number  of  red  cells 
per  cubic  millimetre  may  be  estimated,  except  in  some  special  cases. 

A.     To  Count  the  l^cd  Blood  Corpuscles. 

Appliances— Microscope;  Thoma  corpuscle  counter,  consisting  of  the  ruled 
counting  slide  and  the  diluting  pipettes;  three  small  dishes;  3  per  cent  NaCl  solu- 
tion. 

Technique. — Having  prepared  the  apparatus  and  solutions,  make  the  puncture 
and  fill  the  pipette  by  gently  sucking  a  continuous  column  of  blood  up  to  the  mark 
"05"  or  "1"  on  the  pipette,  which  is  near  the  bulb.  Wipe  the  end  of  the  pipette 
free  from  blood  with  a  clean  cloth,  but  do  not  allow  any  blood  to  be  drawn  out  by 
the  capillary  attraction  of  the  cloth.  As  soon  as  possible  now  insert  the  point  of  the 
pipette  into  the  diluting  solution  and  suck  up  a  continuous  stream  of  solution  until 
the  mark  "101"  above  the  bulb  is  reached.  Roll  the  bulb  between  the  finger  and 
thumb  as  the  blood  enters  the  bulb. 

If  there  is  not  blood  enough  to  reach  the  mark  "1,"  draw  it  only  to  mark  "0.5" 
and  proceed  in  the  same  manner.     Now   hold  the   pipette  in   the  horizontal  position 


20  Outlines  of  Experimental  Physiology 


with  ends  free  and  roll  it  back  and  forth  for  three  minutes  to  thoroughly  mix  the 
blood  and  solution.  When  thoroug-hly  mixed  blow  out  the  contents  of  the  capillary 
below  the  bulb  and  then  place  a  small  drop  on  the  marked  plate  of  the  counting- 
slide,  putting  just  enough  of  the  mixture  on  it  to  fill  the  space  between  the  marked 
plate  and  the  cover-glass,  and  being  careful  not  to  allow  any  of  the  mixture  to  get 
into  the  moat.  Adjust  the  cover-glass,  and  be  careful  not  to  allow  any  of  the 
mixture  to  get  into  the  moat.  Adjust  the  cover-glass  over  the  drop,  quickly  and 
carefully,  by  placing  one-edge  of  cover  glass  in  contact  with  the  slide  and  letting 
the  opposite  edge  down  gently  with  a  needle. 

Place  the  counting  slide,  when  properly  filled,  under  the  microscope  and  find 
the  upper  left-hand  corner  of  the  marked  area.  Wait  until  the  corpuscles  come  to 
rest  upon  the  surface  of  the  marked  plate,  then  begin  the  actual  estimation  by  count- 
ing all  the  corpuscles  in  the  first  marked  space,  including  those  that  are  on  the 
upper  and  left-hand  lines  of  the  space.  Then  count  those  in  the  space  to  the  right, 
including  the  corpuscles  on  the  upper  and  left-hand  lines  as  before.  Continue 
counting  each  space  to  the  right  until  six  spaces  are  counted;  then  drop  down  to  the 
next  space  below  and  count  each  space  to  the  left  until  six  spaces  in  the  second  row 
are  counted.  Then  drop  down  the  next  row  of  spaces  and  continue  counting  back 
and  forth  in  the  same  manner  until  six  rows  of  six  spaces  each  are  counted.  Place 
the  results  of  counting  of  six  rows  in  the  same  relation  to  each  other  as  the  spaces 
that  were  counted. 

Having  made  the  count,  the  slide  and  cover-glass  should  be  cleaned  as  previously 
described.  The  pipette,  which  has  been  left  in  a  horizontal  position  in  a  safe  place, 
should  be  rolled  again  for  three  minutes.  Fill  the  counter  and  adjust  the  cover- 
glass  carefully  as  before;  count  another  group  of  thirty-six  spaces  and  record  the 
results  obtained.  If  the  averages  of  the  two  counts  differ  more  than  one,  the  same 
procedure  must  be  carried  out  the  third  time,  and  the  average  of  the  two  fields 
nearest  alike  taken  and  the  estimate  made. 

To  compute  the  number  of  corpuscles  per  cubic  millimetre,  find  the  average 
number  of  cells  for  each  space  and  multiply  this  by  4000,  as  each  space  is  >^  o  mm.x 
^0  mm.  x  /lO  rnm.  This  will  give  the  actual  number  of  cells  per  cubic  millimetre 
in  the  diluted  blood.  Then  make  the  correction  for  the  dilution  of  the  blood  by 
multiplying  by  100  or  200,  and  the  result  will  be  the  number  of  red  cells  per  cubic 
millimeter  in  the  specimen  of  blood  taken. 

Precautions. — The  cement  used  on  the  counting  slide  is  dissolved  by  alcohol  or 
ether;  so  these  liquids  should  not  be  used  on  the  plate.  Roll  the  filled  pipette  be- 
tween the  thumb  and  finger,  and  do  not  shake  the  pipette,  as  some  of  the  solution  is' 
sure  to  be  lost.  A  common  source  of  error  that  can  easily  be  detected,  but  which  is 
often  overlooked,  is  the  unequal  distribution  of  cells  on  the  marked  plate.  As  soon 
as  the  drop  is  placed  on  the  marked  plate  the  cells  begin  to  settle  and,  of  course, 
most  of  them  settle  where  the  drop  is  thickest,  that  is,  in  the  centre.  This  can  be 
avoided  by  getting  the  cover-glass  in  place  quickly  and  making  the  whole  drop  of 
an  even  thickness.  Each  specimen,  before  being  counted,  should  be  tested  to  see 
that  the  corpuscles  are  evenly  distributed  over  the  whole  drop.  For  the  same  reason 
the  filled  counting  slide  should  be  kept  in  a  horizontal  position. 

Theoretically,  counting  the  cells  in  one  small  space  should  be  sufficient,  and  it 
would  be,  if  the  measurement  and  dilution  of  the  blood  and  the  distribution  of  the 
cells  were  all  perfectly  accurate.     This  is  impossible,   and  the  errors  are  mostly 


Outlines  of  Experimental  Physiology  21 

eliminated  by  the  methods  given.     It   is  best  for  beginners    always  to  make  three 
counts  of  36  spaces  each  from  the  same  pipette  and  take  the  average. 

Questions— 1.   Why  is  alcohol  used  to  dry  and  not  to  clean  the  pipette? 

2.  Why  is  hydrogen  peroxide  used? 

3.  Why  should  the  marked  plate  be  dried  without  friction? 

4.  Why  wipe  away  the  first  drop  of  blood? 

5.  Why  wipe  the  end  of  the  pipette  before  putting  it   into  the  diluting  solution? 

6.  Why  blow  out  a  few  drops  before  putting  a  drop  on  the  slide? 

7.  Whj'  draw  air  through  the  pipette  after  the  ether  is  drawn  out? 

8.  What  kind  of  a  solution  should  be  used  to  dilute  the  blood;  that  is,  what 
properities  should  it  have? 

9.  Why  are  there  101  parts  in  the  pif)ette  instead  of  100? 

10.  Is  there  any  appreciable   variation    in   the   number  of  red  cells  in  normal 
individuals? 

11.  If  there  is  a  variation,  give  some  of  the  reasons. 

12.  Account  for  the  variations  observed  in  members  of  your  section? 


B.      To  Count  the  White  Blood  Corpuscles. 

A  Yi  per  cent  solution  of  acetic  acid  in  distilled  water  will  destroy  the  red  cells 
and  render  them  invisible,  while  it  will  not  destroy  the  white  cells,  but  make  them 
show  more  plainly. 

The  diluting  pipette  holds  solutions  diluted  10  to  100,  instead  of  1  to  100. 

Technique  — The  technique  of  obtaing  the  blood  and  filling  the  pipette  is  the 
same  as  with  the  red  cells,  except  that  the  capillary  tube  is  so  lai-ge  that  we  must 
have  more  blood.  For  this  reason,  for  beginners,  we  recommend  that  only  a  half- 
part  of  blood  be  taken  at  first.  More  accurate  results  can  be  obtained  by  using 
one  part,  but  much  time  and  practice  are  necessary  to  fill  the  tube  easily.  .The 
capillary  is  so  large  that  solutions  Will  not  stay  in  it,  but  run  out  quickly  when  the 
tube  is  out  of  the  horizontal  position.  First,  then,  we  must  have  more  blood;  usually 
two  or  three  good-sized  drops  are  sufficient.  Second,  the  tube  must  be  held  hori- 
zontal or  the  blood  and  solution  will  run  out.  As  the  capillary  tube  is  large  it  is 
very  easly  cleaned  and  dried. 

Roll  the  pipette  as  before,  when  filled,  and  in  a  few  moments  the  mixture  will 
turn  quite  dark;  when  it  no  longer  changes  color  it  is  ready  to  be  counted. 

Allow  a  few  drops  t©  flow  out  of  the  tube  as  in  the  case  of  the  red-cell  pipette, 
then  place  a  small  drop  from  the  end  of  the  pipette  on  the  ruled  plate.  It  is  not 
necessary  to  blow  the  fluid  out;  it  will  run  out.  Take  the  same  precautions  in  fill- 
ing the  counter  and  adjusting  the  cover-glass  as  before,  except  that  there  is  no  need 
of  haste  in  placing  the  cover-glass,  because  the  white  cells  are  lighter. 

Here,  because  we  have  a  clear  field  with  little  in  it,  and  the  cells  are  quite 
large,  we  can  use  a  lower  power  of  the  microscope  and  see  a  whole  square  milli- 
metre at  once.  Place  a  square  aperture  card  in  the  ocular  tube  to  aid  in  defining 
the  field.  Begin  at  the  upper  left  hand  corner  and  count  the  cells  in  each  space 
1  mm.  square,  and  observe  the  same  method  in  keeping  the  record  as  when  counting 
the  red  cells.  Clean  the  counting  slide,  roll  the  pipette  for  a  moment,  and  refill  the 
marked  plate  and  count  the  nine  spaces  again,  keeping  the  records  as  before.  Do 
this  at  least  three  times,  so  that  the   area   counted    will  be  27  spaces,  each  1  mm. 


22  Outlines  of  Experimental  Physiology 


square.  The  more  cells  counted  the  more  accurate  the  results  should  be,  but  the 
three  fields  should  be  sufficient. 

To  estimate  the  number  of  cells  per  cubic  millimeter  in  the  blood  specimen  used, 
add  tog-ether  the  number  of  cells  and  divide  bv  the  number  of  millimetre  spaces 
counted.  Each  space  is  /lo  mm.  x  1  mm.  xl  mm.,  or  /lo  cmm.  Now  multiply 
the  averag-e  number  of  cells  in  each  space  by  10  to  find  the  number  of  cells  in  the 
diluted  blood,  and  then  by  10  or  20,  according-  as  the  blood  was  diluted,  and  that 
will  give  the  number  of  white  cells  per  cubic  millimetre  in  the  blood  specimen. 

Question. — 1.  What  is  the  number  of  white  cells  per  cubic  millimetre  in  the 
blood  in  the  normal  individual? 

2.  What  is  the  normal  variation? 

3.  What  are  some  of  the  causes  of  the  variations? 

(A.j     To  Determine  the  Relative  Volume  of  Red  Corpuscles  and  Plasma. 

Expt.  XI  (a).  Appliances. — Electric  haematocrit;  small  rubber  tubing  to  fit 
capillary  tube;  needle;  white  paper;  fine  wire  for  cleaning- tubes. 

Reagents. — Distilled  water,  hydrogen  peroxide,  alcohol,  ether,  and  lYz  per 
cent  potassium  chromate. 

Preparation. — Adjust  rubber  to  capillar^'  tube.  Put  empty  tube  in  one  arm  of 
cross-piece  to  preserve  balance.  Use  fine  wire  to  remove  blood  from  the  capillary 
tube,  then  clean  and  drj'  as  other  tubes.  Put  vaseline  on  peripheral  rubber  pad  to 
prevent  blood  being  drawn  out. 

Technique. — Obtain  blood  from  the  lobe  of  the  ear  as  heretofore  described.  Re- 
move the  rubber  tube  by  pushing  it  off  and  not  by  pulling,  while  the  vaselined  finger 
is  held  over  the  other  end  of  the  tube.  Remove  any  blood  from  the  Outside  of  the 
capillary,  and  make  a  record  of  the  amount  of  blood  in  the  capillary.  Place  the 
tube  in  the  cross-piece  of  the  instrument  as  quickly  as  possible  and  centrifugalize  at 
least  three  minutes  at  the  rate  of  2,000  to  10,000  rotations  per  minute.  Take  out  the 
tube  and  lay  it  on  a  piece  of  white  paper  to  read  the  divisions.  Each  degree  of  the 
scale  is  estimated  to  contain  about  100,000  cells;  hence,  a  tube  in  which  the  red 
colum  stands  at  50  would  indicate  about  5,000,000  red  corpuscles  per  cubic  milli- 
metre. The  use  of  this  instrument  is  designed,  however,  chiefly  to  show  the  volume 
of  red  corpuscles  rather  than  the  number. 

(b).  When  the  determinations  cannot  be  made  at  the  bedside.  Adjust  the 
rubber  tube  to  the  capillary.  Put  an  emptj'  tube  in  one  arm  of  the  cross-piece  to 
preserve  the  balance  and  vaseline  the  peripheral  pad  of  the  other  arm.  Draw  a 
definite  volume  of  a  2}i  per  cent  solution  of  potassium  chromate  into  the  tube  and 
then  draw  in  blood  from  the  lobe  of  the  ear  to  fill  the  tube.  Determine  accurately 
the  volume  of  blood  in  the  tube,  holding  a  vaselined  finger  over  the  free  end  of  the 
tube  before  pushing  (not  pulling)  off  the  r\ibber.  Place  the  tube  quickly  in  the 
cross-arm  of  the  centrifuge  with  the  blood  end  toward  the  centre,  so  that  the  blood 
is  forced  through  the  solution,  then  proceed  as  in  (a)  to  ascertain  the  volume  of 
plasma  and  corpuscles. 

Precautions. — Do  not  displace  the  rubber  pads  in  the  outer  ends  of  the  rotating 
arm,  as  the  blood  will  be  thrown  out  of  the  tube  and  necessitate  the  repetition  of  the 
test.     Before  starting  each  test  see  that  the  pads  are  in  place. 


Outlines  of  Experimental  Physiology  23 

If  the  tube  is  not  adjusted  in  the  apparatus  and  set  to  rotating-  within  a  few 
seconds  after  the  blood  is  drawn,  coag^ulation  will  set  in  and  hinder  the  complete 
separation  of  the  corpuscles  from  the  plasma.  Should  separation  not  be  complete  in 
three  minutes  the  test  should  be  repeated.  The  instrument  should  be  started  and 
stopped  gradually,  as  the  sudden  starting-  and  stopping-  injures  it. 

Questions — 1.  Determine  the  volume  percentage  of  red  blood  corpuscles  in  a 
number  of  normal  individuals. 

2.  bo  apparently  normal  individuals  have  the  same  or  approximatelj'  the  same 
volume  percentage  of  red  blood  corpuscles  ?  If  not,  seek  for  causes  of  the  variations 
in  different  individuals. 

3.  Does  the  same  individual  have  the  same  volume  percentage  of  red  blood  cor- 
puscles all  the  while  ? 

(a).     If  there  is  a  variation,  is  there  anj*  periodicity  to  be  observed  ? 

{b).     Seek  for  causes  of  any  variation  in  the  same  apparently  normal  individual. 

4.  The  volume  percentage  as  recorded  by  the  haematocrit  varies  with  the  pro- 
duct of  two  factors:  the  average  volume  of  the  individual  corpuscles  by  the  number 
of  corpuscles  per  unit  volume.      (V=vxn). 

{a).     Is  the  average  volume  of  the  individual  corpuscles  (v)  necessarilj^  constant  ? 

{b).  If  it  is  not  constant,  would  one  be  justified  in  drawing  conclusions  regard- 
ing the  number  of  corpuscles  per  unit  volume  (n)  after  observing  the  volume  percent- 
age (V)  with  the  haematocrU  ? 

5.  What  variation  of  the  observation,  as  above  made,  would  enable  one  to  deter- 
mine with  reasonable  accuracy  the  number  of  corpuscles  per  cubic  millimetre  ? 

6.  If  the  tube  were  onlj'  partl3'  filled  at  first,  could  one  make  an  accurate  test  ? 
If  so,  tell  how  to  proceed. 

The  importance  of  some  of  the  above  questions  will  be  better  understood  in 
the  following  experiment. 

B.  The  Determination  of  an  Isotonic  Solution  and  the  Relative  Osmotic  Pres- 
sure of  Dift'erent  Salt  Solutions. 

Literature. — Cohen,  p.  153. 

(a).  Mix2c.c..  2/>^MKCl,  2/^  M  NaCl,  and  2/ g  M  CaClg  each  with  2  c.c.  of 
defibrinated  blood  and  bj'  means  of  the  fine  pipette  fill  three  of  the  haematocrit 
tubes  with  these  mixtures.  Place  the  tubes  in  the  cross  arm  and  centrifugalize  for 
exactlj-  2  minutes.  Note  the  relative  height  of  the  blood  corpuscle  column  in  each 
tube.  Repeat  the  experiment  using  >sM  NaCl,  >s  M  KCl,  >s  M  CaClo  and  then 
'.  16  M  NaCl,  ^s  M  KCl,  >s  MCaClo.  Note  the  relative  height  of  the  blood  cor- 
puscle column  in  each  of  the  series  of  solutions  and  then  compare  the  series  with  the 
other  series.  Why  is  the  serum  colored  red  in  the  third  series?  Do  blood  corpuscles 
follow  the  laws  of  osmotic  pressure? 

One  experiment  must  be  performed  showing  the  relative  volume  of  plasma  and 
corpuscles  of  the  blood  alone,  as  a  comparison  control  for  the  determination  of  the 
relative  pressure  of  the  dift'erent  salt  solutions.  The  isotonic  solution  is  different  for 
different  kinds  of  blood. 

In  order  to  get  good  results  in  these  experiments  the  following  precautions  must 
be  observed:  Have  all  your  apparatus  perfectly  clean,  and  after  washing  with  dis- 
tilled water,  rinse  in  js  M  NaCl.  Ahuays  add  the  blood  to  the  sohitions.  The  cen- 
trifugal tubes  after  being  washed  in  physiological  salt  solution  must  be  rinsed  with 
a  specimen  of  the  blood  to  be  centrifugalized. 


24  Outlines  of  Experimental  Physiology 

Expt.  XII.     The  Estimation  of  the  Percentage  of  Coloring-  Matter  in  the  Blood. 

The  estimation  of  the  coloring  matter  in  the  blood  is  based  on  the  supposed  fact 
that  a  normal  individual  under  normal  surroundings  has  a  normal  amount  of  color- 
ing matter,  and  that  is  called  100  per  cent. 

The  instruments  that  have  been  devised  for  making  the  estimation  are  numerous, 
and  all,  while  theoretically  correct,  practically  are  liable  to  a  greater  or  less  error 
according  to  the  experience  and  carefulness  of  the  observer.  Thej^  are,  howrever,  in 
a  skillful  and  conscientious  operator'.s  hands,  quite  accurate,  and  are  especially  so 
when  used  to  compare  the  tests  of  the  same  patient's  blood,  week  by  week. 

The  haemoglobin  contains  practically  all  the  coloring  matter,  and  it  constitutes 
90  per  cent  of  the  solids  of  the  red  cell.  The  haemoglobin  consists  of  96  per  cent  globu- 
lin and  4  per  cent  haematin.  In  the  haematin  is  the  iron  of  the  corpuscles ;  the  coloring 
matter  of  the  blood  varies  as  does  the  amount  of  iron.  Theoretically,  the  most  accurate 
way  to  test  the  haemoglobin  would  be  to  measure  the  amount  of  iron  in  a  certain 
amount  of  blood.  But  the  chemical  extraction  and  weighing  of  so  small  an  amount 
of  iron  is  too  difl&cult  and  tedious.  Because  of  this,  other  tests  have  been  devised, 
which  depend  upon  the  observer's  eye  to  detect  the  likeness  of  shades  of  red  as  rep- 
resented by  the  blood  and  colored  glass,  solutions  or  paper.  Again,  the  specific 
gravit}'  of  the  blood  except  in  rare  cases  depends  upon  the  amount  of  iron  in  the  red 
cells,  and  varies  as  the  iron  does.  Then  we  can  estimate  the  percentage  of  haemo- 
globin by  finding  the  specific  gravity  of  the  blood. 

The  principal  tests  may  be  classified  as  follows: 

1.  Estimation  of  iron  in  the  blood. 
JoUes'  ferrometer. 

2.  Estimation  of  percentage  of  coloring  matter  bj'  color  tests. 

A.  Fleischl's  haemometer. 

B.  Gower's  haemoglobinometer. 

C.  Dare's  haemoglobinometer. 

D.  Tallquist's  haemoglobinometer. 

3.  Obtaining  the  specific  gravity  of  the  blood  by  Hammerschlag's  method. 
(A).     Fleischl's  Haemometer. 

Appliances.  Fleischl's  haemometer;  needle;  pasteboard  tube  two  inches  in 
diameter;  artificial  light;  small  beaker;  a  dark  room. 

Fleischl's  haemometer  consists  of  a  sliding  colored-glass  wedge  which  moves  in 
a  standard  underneath  a  cylindrical  metallic  cup,  and  a  capillary  tube.  This  cup 
is  divided  into  two  equal  compartments  and  has  a  glass  bottom  and  a  detached 
glass  top.  The  capillary  tube  is  verj'  small  and  is  held  by  a  small  metallic  band 
on  a  handle.  The  glass  wedge  and  the  capillar3^  tube  are  the  important  parts  of 
the  instrument  and  are  made  to  be  used  together.  There  is  a  number  on  the  handle 
of  the  capillar}' tube,  indicating  its  capacity,  and  this  same  number  is  stamped  on 
the  top  of  the  standard,  also  a  number  is  placed  on  the  end  of  the  sliding  frame  that 
holds  the  glass  wedge,  and  the  same  number  appears  on  the  base  of  the  standard  of 
the  instrument  to  which  it  belongs. 

Reagents.     Distilled  water  and  hydrogen  peroxide. 

Preparation  clean  metallic  cell  or  well  with  water  and  dry  with  a  cloth  only 
when  it  needs  it.  The  capillary  tube  should  be  cleaned  with  water  and  hydrogen 
peroxide,  and  then  with  water  again,  by  waving  it  back  and  forth  in  the  solutions 
for  a  moment  or  two.     Then  carefully  dry  the  tube  by  blowing  air  through  it,  hold- 


Outlines  of  Experimental  Physiology  25 

ing-  the  tube  about  two  inches  from  the  mouth  so  as  to  avoid  the  moisture  of  the  ex- 
haled air.  Fill  each  side  of  the  metallic  cup  about  three-fourths  full  of  distilled 
water.      Prepare  the  needle  and  tlie  ear  or  fing-er  as  in  other  tests. 

Technique.     Obtain  the  blood  in  the  usual  manner.     Hold   the  lobe  of  the  ear 
with  the  thumb  and  fing-er.     Use  the  second  drop.     Hold  the  capillary  tube  horizon- 
tally and  Ciirefully  touch  the  drop  of  blood   with  the  end  of   the   tube   only.     If   the 
tube  is  clean  it  will  fill  rapidly  by  capillary  attraction.     If  there  is   any  blood  on 
the  outside  of  the  tube  or  air-bubbles  inside,  it  must  be  cleaned,  dried  and  refilled 
properly.     If  the  capillary  is  overfull,  remove  the  excess  by  touching-  the  tip  to  a 
cloth  or  filter  paper.     Then  quickly  put  the  capillary  tube  into  the  water  in  one 
compartment  of  the  metallic  cell  and  wave  it  back  and  forth  or  up  and  down,  and 
the  blood,  if  fresh  enough,  will  readily  mix  with  the  water;  then  allow  a  few  drops 
of  water  from  the  medicine  dropper  to  fiow  through  the  capillary  into  the  same  com- 
partment to  wash  the  blood  thrtt  sticks  to  the  tube.     Now   fill  each  compartment  al- 
most full  with  distilled  water,  taking  care  that  the  contents  of  either  compartment 
does  not  flow  into  the  other.     Take  the  handle  of  the  capillary  and  stir  the  one  that 
contains  the  blood  so  as  to  make  the  mixture  complete.     Now  carefully'   slide   the 
thick  cover-glass  over  the  compartments  and  gradually  fill  each  cell  with   water   as 
the  cover-g-lass  is  put  on  until  there  is  no  air  left  in  either  cell.     Exclude  daylight 
by   use  of  a  dark  room  and  adjust  the  reflector  so  that  the  artificial  yellow  light  is 
thrown  up  through  the^diluted  blood  and  water  from  the  side  of  the  instrument,  thus 
placing  both  cells  in  the  same  relation  to  the  reflector  and  the  light.     While  making 
the  test  always  shade  the  eyes  from  the  light  by   placing   some   thick   paper   or   a 
pasteboard  tube,  that  reaches  from  the  instrument  to  the  forehead,  before  the  eyes. 
It  is  better  to   use  only  one   eye  at   a  time,   and  look  only  for  a  few  seconds  each 
time,  giving  the  eye  a  rest  and  a  chance  to  regain  the  ability  to  distinguish  tints. 
Stand  at  one  side  of  the  instrument  or  turn  the  instrument  so  as  to  face  the  light  and 
to  bring  the  two  cells  into  similar  relations  with  the  eye.     Begin  with  a  glass  of  a 
lighter  color  than  the  blood,  and  move  the  colored-glass  slide  by  quick  turns   about 
i  one-fourth  of  an  inch  each  time  until  the  color  or  tint  of  the  diluted  blood  appears  to 
I   be  the  same  as  that  of  the  colored   slide;    then   make   the   reading.     Next   turn   the 
(  colored  glass  on  until  it  is  darker  than  the  diluted  blood  and  do  the  same  as  before, 
except    in   the   opposite   direction,  turning  the  slide  until  the  color  of  the  glass  and 
j   blood  are  the  same,  and  then  make  the  reading.     Usually  the   first   reading  will  be 
[  too  low  and  the  second  too  high.     The  difference  will  usually  be  about  10  per  cent. 
The  correct  result  will  be  between  these  two  readings  which  can  now  be  obtained 
In  carefully  moving  the  glass  back  and  forth  or  by  taking  the  middle  point  between 
the    two   readings.     It   is    almost   impossible  to  make  the  reading  accurately  and 
honestly  unless   great  care   is  taken.       The  writer  has  found   the   method  given  to 
produce  by  far  the  best  results.     This  method  should  be  practiced  again  and  again 
I  and  done  with  care.     A  hasty   reading   is    rarely  correct.      Repeat   the    whole   test 
until  you  can  obtain  the  same  result  each  time  with  the  same  individual's  blood. 

Precautions.  If  the  capillary  tube  is  not  perfectly  clean  it  will  not  take  blood 
by  ca.pillary  attraction.  While  cleaning  the  tube  always  test  it  by  touching  a  drop 
of  water,  when  it  should  fill  immediately.  This  will  save  time  and  ensure  quick 
work.     The   amount  of  blood  taken  is  so  small  and  this  is  diluted  so  much  that  the 

i;ast  error  is  multiplied  man}'  times.     We   can   expect    accurate  results  on!}'  when 


26  Outlines  of  Experimental  Physiology 


foreigTi  matter  in  it,  the  tube  will  not  hold  the  right  amount  of  blood  and  the  result 
will  be  too  small.  The  blood  must  be  obtained  and  mixed  in  the  metallic  cup  with 
the  water  very  quickly,  or  it  will  clot  and  stick  in  the  capillary,  or  if  it  does  leave 
it  it  maj'  remain  as  a  clotted  thread  of  blood  in  the  bottom  of  the  cell.  It  takes  a 
little  practice  to  learn  to  wave  the  capillary  in  the  small  space  of  the  cell.  Very 
gentle  constant  waving  back  and  forth,  or  into  the  water  and  out  is  the  most  effective 
in  getting  the  blood  out  of  the  tube.  Too  vigorous  movements  are  liable  to  break  the 
glass  tube.  When  completing  the  filling  of  the  cells  with  water,  fill  the  cell  con- 
taining water  only  first,  and  then  there  is  no  danger  of  getting  any  of  the  diluted 
blood  into  the  water  compartment.  If  you  neglect  to  stir  the  blood  and  water  just 
before  adjusting  the  glass  cover  the  blood  will  remain  in  the  lower  part  of  the  cup 
with  the  water  on  top,  and  it  will  have  a  darker  color  than  it  should  because  the 
blood  reall3^  is  not  as  dilute  as  necessary.  This  v»^ill  give  a  higher  reading  than  is 
accurate.  The  glass  cover  should  always  be  used;  it  not  only  makes  the  amount  of 
dilution  accurate,  but  it  gives  an  even  surface  for  the  transmitted  light  rays.  With- 
out the  glass  the  surface  of  the  water  is  either  concave  or  convex. 

The  metallic  cup  should  not  be  taken  apart  unless  it  is  very  dirty.  If  the  glass 
is  clean,  that  is  sufficient.  As  a  laboratory  precaution,  where  several  instruments 
are  in  use,  alwaj^s  compare  the  markings  to  be  sure  that  you  have  the  capillary  tube 
that  goes  with  the  glass  wedge  that  you  have. 

Questions.  1.  Why  use  distilled  water  to  dilute  blood  and  not  a  saline  solu- 
tion similar  to  the  plasma  of  the  blood. 

2.  Can  different  individuals  make  approximately  the  same  reading  of  the  same 
test? 

3.  Does  everj^  individual  in  ordinar}^  health  have  the  same  percentage  of 
haemoglobin  ? 

4.  How  would  you  explain  the  variation,  if  any  ? 

5.  Do  individuals  who  have  a  low  percentage  of  haemoglobin  have  a  corres- 
pondingly lessened  number  of  red  cells  per  cubic  millimetre? 

6.  Is  the  reverse  of  the  above  true  ? 

(B).     Gowers'  Haemoglobinometer. 

Gowers'  haemoglobinometer  consists  of  three  pieces:  a  capillary  measuring 
pipette,  a  graduated  tube  containing  a  standard  colored  solution.  The  standard 
colored  solution  represents  the  color  of  1  per  cent,  solution  of  normal  blood.  The 
graduated  tube  is  marked  in  100  or  more  parts,  and  each  part  represents  20  c.mm. 
The  capillary  pipette  holds  20  c.mm.  up  to  the  mark  on  the  tube.  If  the  blood  is 
normal  it  will  be  necessary  to  add  water  to  the  hundredth  mark  in  order  to  make 
the  colors  correspond.  If  the  blood  is  not  normal  the  percentage  can  be  read  off  the 
graduated  tube  at  the  top  of  the  diluted  blood  when  the  colors  correspond.  There 
are  two  kinds  of  instruments:  one  for  use  with  daylight,  which  has  a  white  sub- 
stance in  the  sealed  end  of  the  tube  containing  the  colored  solution;  the  other  is  for 
use  with  artificial  light  and  has  a  black  substance  in  the  sealed  end  of  the  tube. 

Reagents.     Distilled  water,  hydrogen  peroxide,  alcohol  and  ether. 

Preparation.  Clean  the  instruments  in  the  usual  manner.  The  capillary 
pipette  should  be  cleaned  with  the  same  care  and  in  the  same  way  as  the  diluting 
pipette,  being  careful  to  first  clean  and  then  to  dry  the  pipette.  Fill  the  graduated 
tube  to  the  mark  20  or  30  with  distilled  water;  prepare  the  needle  and  ear  as  usual. 


Outlines  of  Experimental  Physiology  27 


Technique.  Obtain  the  blood  in  the  usual  way  except  that  a  larg^er  quantit}-  of 
blood  is  needed  than  for  the  preceding-  instrument.  Hold  the  ear  in  the  same  way 
and  fill  the  pipette  as  when  obtaining  blood  in  the  pipette  for  counting  corpuscles. 
Wipe  away  the  first  drop  of  blood.  Touch  the  tip  of  the  pipette  to  the  drop  of  blood, 
resting-  the  pipette  on  the  end  of  the  thumb,  which  is  behind  the  ear,  and  slowly 
suck  the  blood  up  to  the  mark  on  the  pipette,  but  do  not  allow  the  blood  to  go  beyond 
that  point.  If  the  drop  is  not  sufficient,  quickly  obtain  the  second  drop  by  gentle 
pressure  high  above  the  wound  in  the  ear.  If  there  is  any  excess  of  blood  on  the 
point  or  sides  of  the  pipette,  quicklj'  wipe  it  away.  Insert  the  pipette  into  the  tube 
almost  to  the  water  and  SI0WI3'  blow  the  blood,  drop  by  drop  into  the  water.  Now 
immediately  shake  the  tube  to  mix  the  water  and  blood;  this  is  to  prevent  the  blood 
clotting  or  remaining  as  a  thread  in  the  bottom  of  the  tube.  Blood  still  remains  in 
the  capillary  on  its  sides;  so  till  the  pipette  with  distilled  water  and  blow  this  into 
the  tube,  three  or  four  times.  Then  thoroughlj'  mix  the  blood  and  waiter  by  shaking 
or  rolling  the  tube  gently.  Do  not  place  the  thumb  over  the  end  and  shake,  as  an 
appreciable  amount  of  color  will  be  lost  and  a  foam  is  formed  that  delays  the 
reading.    • 

Now  place  the  tube  in  a  rubber  block  beside  the  tube  containing  the  standard 
solution  and  add  distilled  water,  drop  bj'  drop,  to  the  diluted  blood,  always  shak- 
ing the  tube  between  the  additions  to  keep  the  blood  and  water  well  mixed.  Con- 
tinue this  until  the  color  of  the  blood  solution  is  not  darker  or  lighter  than  the  stan- 
dard solution.  The  comparison  of  the  colors  is  made  either  b^-  transmitted  or  re- 
flected daylight.  The  eye  will  be  assisted  by  placing  the  tube  behind  a  piece  of 
white  paper  and  holding  them  toward  the  window  light.  The  reading  is  made 
directly  from  the  graduated  tube,  in  percentage  of  haemoglobin  when  the  color  of 
the  diluted  blood  is  the  same  as  the  standard  solution.  Repeat  the  test  until  the 
same  result  is  obtained  continuall3% 

Precautions.  If  air  bubbles  are  drawn  up  into  the  capillar}',  or  if  it  is  either 
over  or  underfilled,  the  tube  must  be  recleaned  and  dried  and  the  test  repeated  until 
done  accurately.  If  the  pipette  contains  moisture  or  foreign  matter  the  measure- 
ment will  not  be  accurate.  Always  remove  any  blood  that  may  happen  to  get  on  the 
outside  of  the  pipette,  as  it  will  increase  the  result.  It  is  a  good  plan  to  have  a 
large  drop  of  blood  read}'  before  you  begin  to  fill  the  pipette,  rather  than  to  take  two 
or  three  small  drops.  Because  of  the  time  consumed  to  obtain  the  amount  of  blood 
needed  there  is  liabilitj*  of  the  blood  clotting  and  sticking  in  the  capillary.  When 
only  partially  clotted  the  blood  is  blown  into  the  graduated  tube  and  remains  as  a 
clotted  thread  in  the  bottom.  Gently  striking  the  finger  against  the  tube  or  shaking 
the  tube  sidewise  is  sufficient  to  mix  the  blood  and  water,  and  is  far  better  than 
placing  the  thumb  over  the  mouth  of  the  tube  and  shaking  it  up  and  down.  If  this 
latter  method  is  used  it  will  make  a  difference  of  5  to  10  per  cent,  in  results. 
Alwajs  be  sure  to  wash  the  capillar}'  out  a  number  of  times  and  place  the  washings 
in  the  graduated  tube,  or  the  result  obtained  will  be  less  than  the  test  should  show. 
If  a  tube  has  been  partiall}-  or  improperlj-  filled,  do  not  leave  it  so;  always  blow  out 
the  blood  before  it  can  clot,  and  much  time  will  be  saved.  A  reading  should  be 
made  each  time  and  recorded  before  more  water  is  added,  for  if  one  should  dilute 
the  blood  too  much  and  had  no  record  of  the  last  reading  the  test  is  spoiled  and  the 
work  lost. 


28  Outlines  of  Experimental  Physiology 

(C).     Dare's  Haemoglobinometer. 

Preparation.  Dare's  instrument  estimates  the  percentage  of  haemog-lobin  by 
comparing-  the  color  of  a  thin  film  of  blood  of  a  certain  thickness  with  a  revolving 
colored,  wedge-shaped  disk  of  glass.  The  onlj^  preparation  necessary  is  to  clean 
and  polish  the  glass  plates  that  hold  the  blood,  and  adjust  them  in  their  holder. 

Technique.  Obtain  a  good-sized  drop  of  blood  in  the  usual  manner.  Touch 
the  edge  of  the  plates  to  the  drop  of  blood,  and  the  space  between  them  will  be  filled 
with  blood  by  capillary  attraction.  Place  the  holder  in  its  socket  adjust  the  tele 
scopic  tube  and  the  lighted  candle,  and  make  the  reading  in  the  same  manner  as 
with  the  Fleischl  instrument.  A  dark  room  is  not  necessarj',  but  it  is  well  to  hold 
the  instrument  toward  some  dark  object  as  a  background. 

(D).     Tallquist's  Haemoglobinometer. 

Tallquist's  haemoglobinometer  consists  of  a  chart  or  a  paper  on  which  are 
twelve  oblong,  red-colored  stripes,  ranging  from,  10  to  120  per  cent  in  degree  "of  color. 
The  color  of  the  stripe  marked  100  is  supposed  to  be  the  same  color  and  shade  as 
that  of  a  piece  of  filter  paper  in  which  there  is  normal  blood. 

The  other  stripes  vary  from  this  as  the  numbers  indicate. 

Preparations.  '  Take  a  large  piece  of  light  yellow-colored  paper  and  cut  an  ob- 
long hole  in  its  centre,  not  quite  as  large  as  one  of  the  colored  stripes  on  the  chart. 
Take  a  piece  of  the  filter  paper,  at  least  twice  the  size  of  the  colored  stripes,  and  cut 
a  straight  edge  on  one  side  of  the  paper.     Prepare  the  needle  and  ear  as   usual. 

Technique.  Obtain  the  blood  in  the  usual  manner.  Take  the  prepared  piece 
of  filter  paper  and  allow  drop  after  drop  of  blood  to  be  absorbed  into  the  paper  until 
it  is  covered  with  blood  over  an  area  as  large  as  one  of  the  colored  stripes  of  the 
chart.  Put  on  just  enough  blood  to  saturate  the  paper,  no  less  and  no  more.  If 
there  is  too  little  blood  on  the  filter  paper  it  will  "be  white  still  on  the  under  side. 
If  there  is  too  much  blood  on  the  paper  it  will  have  a  glistening  surface,  and  later 
will  clot  upon  the  paper.  This  must  be  prepared  quickly  and  verj'  evenly  and  then 
compared  with  the  stripes  of  the  chart  at  once.  Itwill  be  noticed,  when  the  blood  is 
first  put  upon  the  filter  paper  and  is  still  fresh,  that  it  has  a  glistening  appearance, 
but  that  it  soon  loses  this  and  appears  dull  red  for  a  few  moments,  and  then  it  takes 
on  a  darker  red  appearance  of  clotted  blood.  The  time  to  take  the  reading  is  while 
it  has  the  fresh,  dull-red  color,  just  after  the  glistening  surface  has  disappeared 
and  before  the  dry,  darker  red  color  comes.  This  gives  only  a  few  moments  in 
which  to  make  the  reading.  Place  the  perforated  paper  on  the  colored  chart  and 
place  the  filter  paper  with  the  blood  right  next  to  the  oblong  perforation.  The  ex- 
aminer must  control  his  inclination  to  manufacture  results.  This  is  best  accom- 
plished by  using  the  same  method  as  with  the  Fleischl  instrument.  Do  not  allow 
the  numbers  to  show.  Begin  the  comparison  with  a  colored  stripe  much  lighter 
than  the  blood  specimen  and  move  up  one  stripe  at  a  time  until  the  colors  appear 
the  same;  then  make  a  reading.  Next  begin  with  a  stripe  of  a  darker  color  than  the 
blood  and  compare  colors  in  the  opposite  direction  until  they  appear  the  same,  and 
then  make  a  second  reading.  The  correct  result  will  be  between  these  two  readings 
and  usually  the  two  readings  will  be  10  per  cent  or  more  apart.  The  test  is  made 
by  reflected  daylight.  It  is  well  to  have  a  good  bright  light,  although  direct  sun- 
light is  not  good.  Do  not  let  the  wet  blood  paper  touch  the  chart  as  it  will  destroy 
the  color. 


Outlines  of  Experimental  Physiology  29 

(E).  Estimation  of  Percentag-e  of  Haemog-lobin  of  the  Blood  by  Finding  ihe 
Specific  Gravity. 

The  Specific  gravity  of  the  blood  can  be  obtained  direct  from  a  quantity  of  blood 
as  with  other  solutions.  This  is  not  necessary,  because  when  a  drop  of  any  fluid  is 
put  in  another  fluid  of  the  same  specific  gravity  that  the  drop  does  not  mix  with,  it 
will  go  to  the  center  of  the  latter  fluid  and  remain  there.  If  it  is  lig-hter  it  will  come 
nearer  surface,  ane  if  it  is  heavier,  it  will  sink.  There  area  number  of  solutions 
that  might  be  used.  One  of  the  most  accurate  is  sodium  sulphate  in  solution,  placed 
indifferent  cylinders  in  different  strengths. 

The  specific  gravity  of  the  blood,  except  in  some  cases,  as  in  leukaemia  and 
dropsy,  varies  as  the  amount  of  iron  in  the  corpuscles.  It  must  therefore  be  evident 
that  the  specific  gravitj-  of  the  blood  varies  as  the  percentage  of  haemoglobin  varies. 
'By  consulting  the  table  of  Hammerschlag,  given  below,  the  percentag-e  of  haemo- 
globin can  be  read  for  the  specific  gravitj'of  the  blood  at  once. 

The  most  practical  solutions  to  use  for  finding  the  specific  gravity-  of  the  blood 
are  benzole  and  chloroform,  because  of  the  ease  and  the  speed  with  which  they  may 
be  used. 

TABLE  OF  HAMMERSCHLAG. 

Specific  gravity.  Hjiemoglobin.  Specific  gravity.  Haemoglobin. 

1.033-1.035  =  25-30  per  cent.  1.048-1.050  =  55-65  per   cent. 

1.035-1.038  =  30-35  per   cent.  1  050-1.053  =  65-70  per   cent. 

1.038-1  040  =  35-40  per   cent.  1.053-1.055  =  70-75  per  cent. 

1.040-1.045  =  40-45  per  cent.  1.055-1.057  =  75-85  per   cent. 

1  045-1.048  =  45-55  per    cent.  1.057-1  060  =  85-90  per   cent. 

Appliances.  Specific  gravity  bulb  or  hydrometer;  a  quadrilateral  or  cylindri- 
cal graduated  glass  tube  about  six  inches  high;  a  pipette  or  pointed  '"-lass  rod-  a 
stirring  rod,  and  a  glover's  needle. 

Reagents,  Those  for  cleaning  capillary  pipette,  graduated  tube,  and  needle 
also  benzole  (sp.  gr.  0.879)  and  chloroform  (sp.    g-r.    1  060.) 

The  h3'drometer  is  a  glass  tube  containing  mercurj-  and  air,  and  o-raduated  so 
that  when  placed  in  distilled  water  at  room  temperature  it  reads  1.000. 

Preparation.  Clean  all  apparatus  as  usual,  and  make  a  mixture  of  benzole 
and  chloroform  in  the  glass  tube  of  a  specific  gravity  of  about  1  060. 

Technique.  Secure  the  blood  in  the  usual  vvaj'.  Suck  at  least  three  goodsized 
drops  of  blood  into  the  pipette.  Now  before  the  blood  clots  insert  the  point  of  the 
pipette  into  the  solution  and  blow  out  one  or  two  drops  of  blood,  but  no  air  If  the 
drop  of  blood  goes  to  the  center  of  the  mixture  and  remains  there  after  the  mixture  is 
well  stirred,  then  the  specific  gravity  of  the  blood  is  tlie  same  as  that  of  the  mixture. 
If  the  drop  comes  to  the  top  it  is  lighter  than  the  mixture,  and  benzole  must  be  added 
and  stirred  in.  If  the  drop  goes  toward  the  bottom  it  is  heavier  than  the  mixture, 
and  chloroform  must  be  added.  Add  just  a  few  drops  of  benzole  or  chloroform  at  a 
time  and  stir  well  and  test  before  adding  more.  The  quickness  with  which  the  test 
is  performed  depend  upon  the  carefulness  in  adding  the  benzole  or  chloroform  and 
in  keeping  the  mixture  stirred.  Repeat  the  test  until  the  same  result  is  easily  and 
quicklj'   obtained. 


30  Outlines  of  Experimental  Physiology 


Precautious.  Everything-  must  be  clean  and  dry.  The  blood  will  stick  to  what, 
ever  it  comes  in  contact  with,  the  sides  of  the  graduated  tube,  the  stirring  rod,  or 
the  specific  gravity  bulb,  if  they  are  not  clean  and  dry  There  is  danger,  when  the 
pipette  is  used  to  obtain  the  blood,  of  blowing  small  air-bubbles  into  the  drop  as  it 
is  put  into  the  solution,  which  will  cause  it  to  float.  If  the  mixture  is  lighter  than 
the  blood,  the  drop  will  go  straight  to  the  bottom  and  adhere  with  the  force  of  the 
fall.  The  difficulty  with  the  pipette  can  be  overcome  easily  by  using  a  pointed 
glass  rod.  Secure  the  drop  of  blood  on  the  point  of  the  rod  and  shake  it  off  into  the 
solution.  The  benzole  and  chloroform  evaporate  very  rapidly  and  change  the  speci- 
fic gravity  of  the  mixture.  The  two  liquids  do  not  stay  mixed,  but  need  stirring 
frequently.  Do  not  attempt  to  work  with  the  same  drop  of  blood  more  than  two  min- 
utes. Take  a  fresh  drop  and  continue.  Make  the  specific  gravity  of  the  mixture  as 
near  that  of  the  blood  as  possible  before  adding  the  second  drop.  One  or  two  drops 
will  always  determine  approximately  what  the  specific  gravity  of  the  blood  is;  then 
take  a  third  drop  and  prove  it  exactly.  The  solution  of  benzole  and  chloroform  can 
be  put  into  a  glass-stoppered  bottle  and  used  again;  so  there  is  little  waste  except 
from  evaporation.  This  is  one  of  the  best  tests  for  obtaining  the  percentage  of  hae-, 
moglobin,  as  the  personal  equation  is  largely  eliminated  and  the  burden  of  accuracy 
is  placed  upon  the  instrument. 

QUESTIONS. 

1.  Why  make  the  mixture  1.050  to  begin  with? 

2.  What  is  the  specific  gravity  of  benzole?     Of  chloroform? 

3.  Why  are  they  better  than  other  solutions  for  a  quick  test? 

Expt.  XIII.  Microscopic  Test  for  Blood  Pigment.  Put  a  drop  of  blood  on  a 
slide  and  let  it  dry.  Add  a  drop  of  strong  glacial  acetic  acid.  Add  a  grain  of  NaCl 
put  on  a  cover  glass  and  heat  gently  till  the  liquid  begins  to  boil.  Cool  and  exam- 
ine with  the  high  power.  Small  brownish  black  crystals  of  haemin  will  be  seen. 
This  is  an  important  test  in  medico-legal  cases.  Apply,  this  test  to  blood  stains 
from  a  piece  of  cloth.  Soak  the  cloth  in  a  small  quanity  of  NaCl  solution.  Evapo- 
rate to  dryness  and  put  on  acetic  acid  and  proceed  as  above. 

Expt.  XIV,     Spectroscopic  Examination  of  Haemoglobin  and  its    Derivatives. 

With  a  Spectroscope  look  first  at  a  bright  part  of  the  sky.  Focus  until  the  num- 
erous fine  dark  lines  (Frauenhofer's)  running  vertically  across  the  spectrum  are  seen. 
Narrow  the  slit  by  moving  the  milled  edge  till  the  lines  are  sharp.  Note  especially 
the  lines  D  in  the  orange,  E  and  b  in  the  green  and  F  in  the  blue.  Always  hold 
the  spectroscope  so  that  the  red  is  in  the  left  of  the  field,  (a)  Now  moisten  a  plati- 
num loop  with  H2O,  dip  in  NaCl  and  hold  in  a  fishtail  flame.  Exam- 
ine with  the  spectroscope.  A  bright  yello;v  line  will  be  seen  occupying  the  posi- 
tion of  the  D  line  in  the  solar  spectrum.  This  is  a  convenient  line  of  reference  in 
the  spectrum  and  in  studying  the  spectra  of  haemoglobin  and  its  derivatives,  the  po- 
sition of  the  D  line  with  regard  to  the  absorption  bands,  should  always  be  noted. 
The  dark  lines  in  the  solar  spectrum  are  due  to  the  absorption  of  light  of  a  definite 
range  of  wave  lengths  by  metals  in  a  state  of  vapor  in  the  sun's  atmosphere,  and  of 
course  no  dark  lines  are  seen  in  the  spectrum  of  a  gas  flame.  Arrange  the  spectro- 
scope, flame  and  test  tube  on  a  table.     Half  fill  a  test  tube  with  defibrinated   blood. 


Outlines  of  Experimental  Physiology  31 


Nothing-  can  be  seen  with  the  spectroscope  till  the  blood  is  diluted.  Pour  a  little  of 
the  blood  into  another  test-tube  and  g-oon  diluting  until,  on  focusing-,  two  bands  of 
oxyhaemoglobln  are  seen.  Draw.  Dilute  more, — which  of  the  bands  first  disap- 
pear?    How  dilute  was  the  blood?     One  drop  of  blood  to  50  c.  c,  HoO=l:750. 

(b).  Make  a  solution  of  blood  which  shows  the  oxyhaemog-lobin  bands  sharply. 
Add  20  drops  of  strong- ammonium  sulphate  solution  to  reduce  the  oxy haemoglobin. 
Heat  gentl}'  to  the  bodj'  temperature  or  add  a  few  drops  of  freshly  prepared  Stokes 
fluid  (ferrous  sulphate  and  tartaric  acid,  each  the  size  of  a  pea,  dissolve  in  H2O, 
make  alkaline  with  ammonia  hydroxide,)  gives  a  clear  green  solution;  now  shake  it 
so  as  to  mix  it  with  air  and  note  the  oxyhaemoglobin  band  appear.     Why? 

U).  Carbonic  oxide  haemoglobin.  Pass  coal  gas  through  blood  for  some  time. 
Dilute  and  examine.  Two  bands  almost  in  the  position  of  the  oxyhaemoglobin  band 
are  seen  but  no  change  is  caused  by  the  addition  of  ammonium  sulphide,  since  car- 
bonic acid  haemoglobin  is  a  more  stable  compound  than  oxyhaemoglobin.  Now 
shake  it  with  air.     Does  the  oxyhaemoglobin  band    appear? 

(d).  Methaemoglobin.  Put  some  blood  in  a  test  tube,  add  a  few  drops  of  strong 
potassium  ferricyanide  and  heat  gentl}'.  Dilute,  examine.  A  well  marked  band 
will  be  seen  in  the  red.  On  addition  of  ammonium  sulphide,  this  band  disappears; 
the  oxyhaemoglobin  bands  are  seen  for  a  moment  and  then  g-ive  place  to  the  reduced 
hiiemoglobin  band.     Shake  in  air.     Results? 

{c).  Dilute  a  solution  of  eosin  or  picro  carmine  with  water  until  it  has  the  shade 
of  blood  that  gives  the  two  ox3iiaemoglobin  absorption  bands.  If  the  two  bands  ap- 
pear, test  with  Stokes  fluid  or  strong  NH  4  S.     Result?     Mix  with  air.     Result? 

Literature. — Ziemke  and  Muller,  Archiv  fur  Anat.-Phys.     1901,  Sp.  Bd,  177. 

Test  for  Carbon-monoxide  Blood. 

Expt.  XV.  (I),  Kunkel's  test.  (a).  Mix  carbon-monoxide  blood  with  four 
times  its  volume  of  water.  To  a  measured  quantity  of  this  mixture  add  an  equal 
volume  of  3  per  cent  tannin  solution.     Note  the  change  in  a  few  hours. 

(b).  Repeat  (a)  with  normal  blood;  let  stand  a  few  hours  and  compare  with  (a). 
Result? 

Precipitin  Test  for  Human  Blood,  Medico  Legal  Test. 

Expt.  XVI.     See  Nuttall.  Blood  Immunity,  1904. 

The  Action  of  the  Valves  of  the  Heart. 

Expt.  XVII.  From  the  mammalian  heart,  note  the  form,  structure  and  attach- 
ment of  all  the  valves  in  the  heart.  Observe  the  difference  between  the  walls  of  the 
veins  and  arteries,  the  left  and  right  auricles  and  ventricles. 

(a).  Illustrate  on  the  mammalian  heart,  the  position  of  the  blood  vessels  semi- 
lunar and  auriculo-ventricular  valves  on  a  median  section  of  a  heart  or  show  dia- 
grammatically  the  action  of  the  valves  and  the  course  of  the  blood  through  the  heart 
after  having  studied  the  following  experiment 

(b).  Tie  a  wide  glass  tube  (A)  lOcm.  long  in  the  left  auricle  and  one  (B)  5Ucm. 
long  into  the  aorta.  Ligate  all  the  other  blood  vessels  of  the  left  side  of  the  heart. 
Connect  A  with  a  faucet  by  rubber  tubing  and  place  the  heart  in  a  large  dish. 
Let  water  flow  into  the  heart  and  support  B  by  a  clamp  to  a  stand.     When  the  water 


32  Outlines  of  Experimental  Physiology 

stands  on  a  level  in  both  tubes,  compress  the  ventricle.  In  which  tube  does  the 
water  stand  higher?  Relax  the  pressure.  What  is  the  effect?  Why?  By  alter- 
nately compressing-  the  ventricle  and  allowing-  it  to  relax,  water  can  be  sent  into  the 
aorta  tube  to  overflowing  into  the  left  auricle,  imitating-  one-sided  circulation. 

(c).  Pour  water  into  the  pulmonary  artery  and  note  the  semilunar  valves.  Make 
an  incision  into  the  right  auricle  and  one  in  the  right  ventricle  so  that  you  can  see 
the  tricuspid  valves;  study  its  action  by  pouring  water  into  the  ventricular  incision 
and  also  into  the  auricular. 

The  Circulation  Scheme. 

Expt.  XVIII.  With  this  apparatus  the  physical  phenomena  of  the  circulation 
may  be  thoroughly  studied.  Describe  (1)  the  conversion  of  the  intermittent  into 
the  continuous  flow.  (2).  The  relation  between  the  rate  of  the  flow  and  the  width 
of  the  bed.  (3).  The  relation  of  peripheral  resistance  to  blood  pressure.  (4).  The 
period  of  outflow  from  the  ventricle.  (5).  The  pulse  waves.  (6).  Compare  venous 
with  arterial  pressure. 

The  flow  of  blood  through  the  arteries,  veins  and  capillaries  follow  the  laws 
which  govern  the  flow  of  any  liquid  through  a  system  of  tubes,  so  that  we  are  able 
to  illustrate  many  features  of  blood  flow  by  means  of  an  artificial  arrangement 
of  tubes  drawn  up  in  imitation  of  the  circulatory  mechanism.  The  rubber  bulb  pro- 
vided with  valves  which  permit  the  flow  of  the  fluid  in  one  direction  only,  represents 
the  heart.  (Left).  One  manometer  is  situated  in  the  course  of  the  arterial  system* 
represented  by  rubber  tubing  connected  with  the  bulb  at  the  end  having  the  out- 
flowing valve.  The  other  manometer  is  beyond  the  two  branches  that  anastomose 
to  form  one  vein.  The  tube  filled  with  wood  fibre  represents  the  capillaries;  the 
tubing  from  there  on,  the  veins. 

(b).  When  a  pump  forces  water  or  any  other  incompressible  fluid  through 
tubes  with  rigid  walls,  the  inflow  and  outflow  are  equal  and  in  the  same  time.  The 
outflow  ceases  the  instant  the  inflow  ceases.  The  same  is  true  in  a  system  of  elastic 
tubes  so  short  and  wide  that  friction  between  the  liquid  and  the  walls  causes  prac. 
tically  no'resistance  to  the  flow.  Here  the  quantity  received  from  the  pump  can  still 
escape  from  the  distal  end  of  the  system  during  the  stroke  of  the  pump.  When  this 
resistance  is  increased  bj'  narrowing  the  tubes  or  increasing  their  length,  or  in  both 
ways,  not  all  the  liquid  received  from  the  pump  can  pass  by  the  resistance  during 
the  stroke  of  the  pump;  the  remainder  must  pass  during  the  interval  between  one 
stroke  and  the  next.  This  portion  which  cannot  pass  during  the  stroke,  finds  room 
between  the  pump  and  the  resistance  by  the  dilation  of  the  containing  vessels.  To 
efl'ect  the  dilation,  the  force  or  pressure  transmitted  from  the  pump  presses  out  the 
vessel  walls  until  this  pressure  is  held  in  equilibrium  by  the  elastic  -reaction  of  the 
walls  As  the  pressure  from  the  pump  wanes,  the  energy  stored  by  it  in  the  tension 
of  the  vessel  walls  is  reconverted  into  mechanical  motion  and  the  walls  return 
toward  their  original  position,  driving  the  liquid  out  of  the  tube,  past  the  resistance- 
In  using  this  scheme,  only  slightly  compress  the  bulb  at  each  beat.  Watch  the 
arterial  manometer  and  be  careful  not  to  force  the  mercury  out  of  it. 

•  1.  Open  the  side  branch  by  unscrewing  the  pressure  ,  clip.  See  that  the  tubes 
are  free  from  air  and  well  filled  with  water.  To  get  rid  of  the  air  hold  the  tubes  up 
with  the  right  hand  while  filling  with  water.     Make  a  single,  brief,  gentle  pressure 


Outlines  of  Experimental  Physiology  33 

on  the  bulb.  (Note  1)  That  practically  all  the  liquid  driven  out  by  the  stroke  escapes 
throug-h  the  side  branch  in  which  the  resistance  is  low  rather  than  throug-h  the  hig-h 
capillary  resistance.  (2).  Only  a  portion  of  the  liquid  escapes  throughout  the 
stroke.  (3).  The  portion  which  cannot  escape  by  the  resistance  during  the  stroke 
finds  space  in  a  very  evident  dilation  of  the  tubes  nearer  the  pump;  i.  e.,  between 
the  pump  and  the  principal  resistance.  The  membrane  manometer  shows  a  sudden 
rise  and  fall  indicating  a  sudden  rise  and  fall  in  the  intraventricular  pressure. 

Fill  the  bend  of  the  manometers  with  mercury  and  the  whole  apparatus  with 
water,  all  air  being  expelled.  Open  the  clip  opposite  the  capillaries.  You  will 
now  study  the  flow  along  a  closed  system  of  elastic  tubes  without  peripheral  resist- 
ance, if  the  extremity  tubes  are  connected.  Now  imitate  the  beating  of  the  heart  by 
rhythmical  pressure  of  the  bulb, — gradual!}'  increase  the  rate.  Study  the  move- 
ment of  the  pulse  and  note  the  following. 

(1).  Compare  the  movements  of  the  two  manometers  in  time  and  amplitude. 
(1).  Note  the  effect  of  the  vein  tube  and  the  manometers  when  the  bulb  is  filling 
(diastole).  (3).  Close  the  clip,  thus  interposing  high  resistance,  and  pump  fluid 
through  the  system  as  before.  Note  the  effect  of  the  systole  on  both  manometers. 
What  is  the  effect  of  diastole  on  both  manometers?  What  is  the  result  if  only  one 
emptying  of  the  bulb  is  carried  out — i.  e.,  after  ocilliations  have  ceased?  What  is 
the  result  if,  before  the  pressure  becomes  equalized,  the  bulb  be  once  more  emptied, 
before  the  second  effect  has  passed  off?  What  is  the  effect  on  the  manometer  of 
about  20  strokes  at  a  definite  rate?  Does  the  rise  in  pressure  occur  at  the  instant 
the  bulb  is  compressed?  Can  you  feel  a  pulse  or  pressure  wave?  Is  there  a  nega- 
tive pressure  formed  and  where?  What  important  condition  found  in  the  circulation 
is  produced  by  this  scheme?     How  could  the  scheme  be  improved? 

B.  The  Conversion  of  the  Intermittent  Into  the  Continuous  Flow. 

(1).  With  the  side  branch  open,  compress  the  bulb  rhythmically,  gradually  in- 
creasing the  frequenf'y  of  the  stroke.  It  will  be  found  that  with  few  strokes  the 
stream  will  be  intermittent.  As  the  interval  between  the  strokes  is  shortened, 
the  liquid  received  from  the  pump  in  any  one  stroke  cannot  all  escape  by  the  resist- 
ance during  the  stroke  and  the  succeeding  interval.  The  next  stroke  comes  before 
the  outflow  from  the  preceeding  stroke  is  finished,  and  the  stream  becomes  remit- 
tent. 

Still  further  increase  the  frequency  of  the  stroke.  A  rate  may  be  reached  at 
which  the  intermittent  will  be  converted  into  the  continuous  flow. 

Observe  that  the  duration  of  the  interval  is  greater  than  the  duration  of  the  . 
pump.  Thus  the  greiiter  part  of  the  tim2,  the  circulation  is  carried  on,  not  by  the 
direct  stroke  of  the  pump,  but  the  energy  stored  up  by  the  pump  in  the  elastic  walls 
of  the  vessels.  Note  that  the  arterial  pressure  remains  low  evea  after  this  stream 
becomes  continuous.  An  increase  in  the  frequency  of  the  beat  has  little  influence 
on  the  blood  pressure  when  the  peripheral  resistance  is  slight.  Record  pressure  in 
millimeters  of  mercury. 

(2).  Close  the  side  branch,  not  completely,  but  so  that  the  liquid  must  pass 
through  a  high  peripheral  resistance  Compress  the  bulb  at  such  a  rate  that  the 
outflow  shall  be  continuous.  Be  careful  not  to  force  the  mercury  out  of  the  arterial 
manometer — Compress  the  bulb  only  partially.     Compare  the   frequency  required  to 


34  Outlines  of  Experimental  Physiology- 


make  the  flow  ccntinuous  now,  with  that   required    when   the   peripheral  resistance 
was  low. 

N.  B.  The  capillaries  sometimes  becom'e  clog-g-ed  up  with  particals  from  the 
water.     If  that  happens,  speak  to  the  instructor. 

(3).  The  relation  of  the  peripheral  resistance  to  blood  pressure.  Compress 
the  bulb  at  such  a  rate  that  a  continuous  flow  will  be  produced.  With  each  success- 
ive stroke  the  portion  of  liquid  unable  to  pass  the  resistance  during  the  stroke  and 
the  succeeding  interval,  is  added  to  that  left  behind  from  the  preceding  strokes.  The 
arteries  become  more  and  more  full.  The  arterial  manometer  registers  a  higher  and 
higher  pressure.  At  length  the  mercury  ceases  to  rise.  The  mercury  remains  at  a 
mean  level  broken  by  a  slight  oscillation  at  each  stroke.  The  pump  now  merely  re' 
tains  the  constant  high  arterial  pressure.  This  pressure  suffices  to  drive  through 
the  resistance  during  each  stroke  and  the  succeeding  interval,  all  the  liquid  received 
from  the  pump  during  the  stroke. 

Is  the  venous  pressure  high  or  low?  Why?  Is  there  a  pulse  on  the  venous  side 
of  the  resistance?     Why? 

(D).  Inhibition  of  the  ventricle.  While  the  arterial  pressure  is  at  a  good 
height  (120  mm  Hg)  arrest  the  ventricular  stroke.  (The  s'entricle  in  animals  may  be 
thus  inhibited  b}'  stimulation  of  the  vagus  nerve.)  Observe  the  arterial  manometer 
and  explain.     Resume  the  ventricular  beats      Explain  the  effects  on  pressure. 

The  pulse  curve.  Cover  the  thistle  tube  of  the  sphygmograph  (thistle  tube)  with 
thin  sheet  rubber  and  cement  a  bone  button  to  the  center  of  the  membrane.  Connect 
the  tambour  thus  formed  with  a  recording  tambur.  Bring  the  writing  point  against 
a  slow  moving,  lightlj'  smoked  drum.  While  the  pump  maintains  a  moderate  pres- 
sure (about  50mm  Hg),  adjust  a  button  on  the  aorta  and  then  (not  sooner),  close  the 
side  branch  of  the  sphj-gmograph  tube.     Record  a  series  of  pulse  curves. 

Note  a  quick  up-stroke  corresponding  to  the  quick  distention  of  the  artery  by 
the  emptj'ing  of  the  ventricles  and  the  gradual  down-stroke,  corresponding  to  the 
gradual  emptying  of  the  artery  through  the  resistance  during  the  diastole  or  interval 
between  two  beats. 

The  down-stroke  is  broken  by  several  small  waves  caused  by  the  oscillation  of 
the  mercury  in  the  arterial  manometer.  Near  the  apex  of  the  more  delicately  written 
curves,  may  be  seen  a  slight  depression,  the  dicrotic  notch, — this  wave  is  more  easily 
studied  in  human  pulse  curves. 

Low  Tension  Pulse.  Open  slightly  the  side  branch  that  permits  the  liquid  in 
the  arterial  tubes  to  flow  out  without  passing  through  the  resistance.  The  arterial 
pressure  will  fall  in  con  sequence  of  the  diminished  peripheral  resistance.  Normally, 
this  effect  is  produced  by  dilation  of  the  smaller  arteries.  Let  the  arterial  pressure 
sink  to  about  20  mm  Hg. 

Record  a  series  of  pulse  curves. 

The  oscillations  of  the  mercury  column  are  much  lighter  than  with  normal  pres- 
sure (120—150  mmH'^).  Feel  the  pulae  with  the  finger.  At  each  beat  the  artery  quickly 
expands  and  as  quickly  relaxes      The  artery  is  softer  than  usual. 

High  Tension  Pulse.  Close  the  side  branch  almost  entirely  so  that  all  the  water 
has  to  pass  through  the  porous  wood.  What  is  the  effect  on  arterial  pressure?  Be 
very  careful  not  to  compress  the  bulb  too  hard  in  this  experiment  as  the  mercury 
will  otherwise  be  forced  out  of  the  manometer. 


Outlines  of  Experimental  Physiology  35 


Hardy's  Experiments  on  Colloids. 

Expt.  XIX.  Put  some  of  the  prepared  acid  heat-modified  proteid  into  one  of 
the  U  tubes  supported  on  the  stand,  tilling,''  it  to  within  an  inch  of  the  top.  Adjust 
the  platinum  electrodes  so  that  they  are  immersed  in  the  solution  and  connect  with 
six  batteries  placed  in  series  or  electric  lifj;-hting-.  using-  g-round  g-lass  and  carbon  re- 
sistance =  .000001  C  Prepare  another  tube  of  alkaline  proteid  in  the  same  way  a 
third  of  neutral  and  a  fourth  of  undialyzed  albumen  and  introduce  into  the  same 
circuit.  Watch  the  experiment  through  the  day  and  ag-ain  the  next  day  if  uo  defi- 
nite collection  and  precipitation  of  proteid  has  occurred.  Where  does  the  proteid 
collect?     and  why? 

The  heat-modified  proteid  is  prepared  by  diluting-  white  of  eg-g-  with  nine  vol- 
umes of  distilled  water,  filtering  and  boiling.  The  resulting  liquor  must  be  blue 
and  transparent  The  first  portion  of  the  boiled  proteid  is  white,  owing  to  the  sur- 
face action  of  the  glass  and  should  be  thrown  away.  The  colloidal  solution  is  then 
dialyzed  seven  days  in  a  cool  place,  covered  and  boiled  to  remove  the  salts.  Those 
who  wish  can  prepare  some  ot  this  proteid  as  an  extra  experiment. 

Acid  or  alkaline  proteid  is  made  by  adding  a  trace  of  acetic  acid  or  KOH 
Dip  a  needle  into  KOH  per  cent,  wash  this  in  cc  distilled  water  and  from  this  take 
a  needle  full. 

(2).  Colloidal  Ferric  Hydrate  is  prepared  as  follows;— To  a  fairly  dilute  solu- 
tion of  Ferric  chloride,  ammonium  hydrate  is  added  until  a  slight  permanent  pre. 
cipitate  of  Ferric  Hydrate  is  formad.  This  is  redissolved  by  adding  a  little  Ferric 
Chloride  to  the  solution.  This  mixture  is  subjected  to  a  prolonged  dialysis  of  seven 
weeks  in  distilled  water  to  remove  the  salts  in  the  mixture  The  solution  is  neu- 
tral. Put  some  of  the  prepared  Ferric  hydrate  in  a  U  tube,  subject  it  to  the  electri- 
cal current  of  105  volts  for  24  hours      Note  the  region  of  coagulation. 

(3).  Test  coagulation  of  ferric  hydrate  solution  by  ions.  Prepare  test  tubes, 
each  containing  4c.  c.  of  the  salt  solutions  provided.  All  are  m/100  solutions. 
Have  also  a  tube  of  distilled  water  as  a  control.  To  each  tube  add  three  to  five 
drops  of  the  ferric  hydrate  solution.  With  which  salts  does  precipitation  take  place 
at  once?  Which  precipitate  on  warming?  Repeat  with  those  that  do  not  precipi- 
tate at  once,  letting  the  tube  stand  without  warming  till  the  end  of  the  day.  Try 
solutions  of  cane  sugar  of  various  strengths.  Ascertain  the  weakest  solution  of 
MgS04  that  will  cause  the  immediate  precipitate  (say  in  two  minutes)  of  ferric  hy- 
drate. Repeat  with  MgCU,  NaCl,  Na2HP04,  AloiSOi)^,  CuSO*,  CuClg,  K3SO4, 
CaCls,  Na2S04. 

(4).     Test  the  effect  of  the  salts  employed  in  (3)  on  acid  heat  modified    proteid. 

(5).  Test  the  eflfect  of  the  salts  employed  in  (3)  on  alkaline  heat  modified  pro- 
teid. 

(a)  Arrange  the  results  of  all  the  tests  in  a  table,  giving  results  both  with  and 
without  heat. 

Literature.     Journal  of  Physiology,  Vol.  24,  p.  289.     Mann    p.  37. 


36  Outlines  of  Experimental  Physiology 

Effects  of  Lack  of  Oxygen  and  KCN  upon  Cells. 

Expt.  XX.  (a)  Place  several  drops  of  Paramoecia  or  Vorticella  culture  in  an 
Eng'leman  or  capillary  gas  chamber.  Cover  the  edges  of  the  chamber  with  vase- 
line and  close  tightly,  making  sure  that  no  air  can  enter.  Connect  the  chamber 
with  your  hydrogen  generator.  Wash  the  glass  as  usual  and  keep  up  a  slow  stream 
through  the  chamber.  From  the  chamber  pass  the  gas  into  a  breaker  of  water. 
Note  carefully  the  behavior  of  the  Paramoecia,  and  make  drawings  of  the  changes 
produced  in  the  cells. 

(b)  If  yoti  have  time  to  repeat  the  experiment,  use  a  hanging  drop  of  the  culture 
and  study  the  changes  with  the  high  power,  after  half  an  hour. 

(c)  To  several  drops  of  Paramoecia  culture  in  a  watch  glass  under  the  micro- 
scope, add  one  drop  of  an  0.1  per  cent  solution  of  KCN.  Note  the  effects  and  draw. 
Use  the  micrometer  scale  and  compare  with  the  normal  form. 

(d)  Repeat,  using  a  0.5  per  cent  solution  of  KCN. 

What  conclusions  do  j'ou  draw  as  to  the  comparative  effects  upon  the  cell  of  KCN 
and  a  lack  of  oxygen?     Explain  why  KCN  is  toxic. 

See  Lyon's  paper.     A.  M.  Journal  of  Phys.     Vol.  VIII.  p.  56. 

Ciliary  Motion. 

Expt.  XXI.  Cut  the  frog  in  two,  midway  between  the  fore  and  hind  limbs. 
Remove  the  anterior  body  wall  and  all  the  viscera,  except  the  oesophagus  and  the 
upper  part  of  the  stomach.  Remove  the  arms,  cut  away  the  lower  and  upper  jaw  on 
a  level  back  of  the  eyes,  and  slit  up  the  oesophagus  in  the  mid-ventral  line. 
Through  an  opening  made  between  the  mucous  lining  and  the  skull,  pass  the  glass 
plate  between  the  oesophagus  and  the  vertebra.  Stretch  out  the  oesophagus  and 
the  stomach  and  fix  them  with  pins  on  the  cork  each  side  of  the  glass  plate. 

(a)  Place  a  small  wooden  or  cork  block  on  the  mucous  membrane  at  the  end 
near  the  head  of  the  frog.     It  will  be  carried  along  towards  the  stomach. 

(b).  Repeat  the  experiment,  placing  a  wedge  under  the  cilia  board.  In  what 
direction  do  the  cilia  lash  particles? 

(c).  Weight  the  block  with  lead  weights  and  determine  how  great  a  load  can  be 
carried  on  a  level  and  up  an  incline  plane.  The  mucous  membrane  should  be  wet 
with  normal  saline  solution.     (Avoid  excess). 

(d).  Cauterize  with  a  hot  wire  superficially  a  small  area  of  mucous  membrane 
in  a  preparation  thinly  bestrewn  with  charcoal.  Does  the  action  of  the  cilia  in  the 
neighboring  parts  change?  Are  the  movements  depended  upon  stimuli  from  neigh- 
boring cells?     What  kind  of  an  area  is  affected?     What  does  this  show? 

(e).  Cauterize  two  parallel  lines  (very  short)  first  longitudinally,  then  across. 
Effect  on  the  charcoal  movements? 

(/■).  Try  NaCl  (normal)  at  35°  C  on  the  membrane,  noting  the  time  of  the  move- 
ment before  and  after. 

Expt.  XXII.  From  the  edge  of  the  gill  of  a  clam  or  oyster,  snip  off  a  small 
piece  and  mount  in  the  animal's  own  fluid  and  examine  with   low    and  high  powers. 

(a).  Make  a  careful  study  of  the  rapid  movement.  What  is  its  object?  Watch 
the  progressive  slowing. 

(b).  Tease  out  single  cells  from  the  mass.  Does  the  movement  continue?  If  so, 
does  it  differ  from  that  of  the  mass?     Illustrate. 


Outlines  of  Experimental  Physiology  37 


(c).  Apply  heat  with  a  lamp  or  the  warm  chamber  of  the  microscope  to  the  pre- 
paration and  observe  the  effect.  At  what  temperature  is  the  movement  most  violent? 
When  do  movements  betrin  to  slow?,  stop?     Apply  cold  to  another  specimen. 

(d).  Find  a  spot  in  which  the  movements  are  very  slow  and  study  the  action  of 
a  single  cilium  when  in  the  position  at  rest.  What  is  its  path  vvhen  rapidly  moving-? 
Sketch. 

Expt.  XXIII.     The  influence  of  Stimulants  and  Narcotics  on  Ciliary  Movements- 

Prepare  a  slide  with  cilia  in  a   so-called   gas   chamber;   two  gas    flasks  joined 

each  to  a  faucet  and  through  a  T  with  each  other.     At  the  free   end   of   the  T  attach 

another  T  and  from  each  free  end  of  the  latter,  rubber  tubing  joins  the    inlet   tube  of 

the  gas  chamber,  while  the  tubing  from  the  outlet  tube  ends  in  a  ghiss  of  water. 

(To  obtain  the  CO 2  gas,  use  CaCOs  and  HCl  or  obtain  it  from  a  CO 2  cylinder). 
Fill  a  flask  with  water  and  displace  with  the  gas.  In  the  other  flask  put  either 
oxygen  or  hydrogen.  The  flow  of  gas  is  regulated  by  means  of  the  flow  of  water 
and  clamps,  one  of  which  is  on  each  side  of  the  T. 

Prepare  a  specimen  of  cilia  for  observation  with  the  low  power  microscope. 
Bring  a  good  specimen  into  the  field,  observe  the  rate  and  character  of  the  move- 
ment. Allow  a  slow  stream  of  CO 2  to  pass  in.  Observe  the  effect  If  no  effect  oc- 
curs, repeat  the  dose  of  gas.     Results? 

(a).  After  the  effect  has  become  apparent,  clamp  the  tubes  and  draw  in  fresh 
air,  thus  restoring  normal  conditions.  What  is  the  effect?  How  many  times  may 
cilia  be  restored  to  activity  by  ventilation?  after  having  been  completely  stopped 
by  CO  2? 

(c).  Try  oxygen.  (Heat  oxygen  mixture,  MnO^  &  KCIO3  for  20  minutes). 
What  happens? 

(d).  Chloroform  gas  on  cilia  movements.  Take  a  new  preparation  of  cilia  and 
observe  the  normal  movement.  Place  cotton  saturated  with  chloroform  in  a 'flask 
and  allow  the  gas  to  pass  through  the  chamber.  Note  the  effect.  How  many  times 
may  the  cilia  be  revived? 

(e).     Use  alcohol  instead  of  chloroform.     Results? 

(/).     Use  0.4  per  cent  formole. 

(^).     Tobacco  smoke  may  be  tried. 

(h).     Try  dilute  acids  and  alkalies,  0.1  per  cent  each. 

(/).     Dissolve  out  salts  with  distilled  water  }^  hour  and  revive  with  NaCl. 

The  Kymograph. 

Make  yourself  acquainted  with  the  instrument.  Learn  how  to  wind  it,  not  too 
tightly;  how  to  start  and  stop  the  clockwork;  how  to  raise  and  lower  the  drum;  and 
how  to  change  the  .speed.  Always  remove  the  fans  by  a  steady  even  pull  directly  in 
line  with  the  spindle  on  which  they  revolve.  Never  wiggle  the  fans  from  side  to 
side  on  the  spindle  On  the  old  kymographs,  the  speed  may  be  regulated  by  turn- 
ing the  milled  head  to  which  the  pointer  is  attached. 

To  put  the  paper  on  the  drum.  Lay  the  sheet  of  paper  flat  upon  the  table, 
moisten  the  gummed  end,  lay  the  drum  across  the  paper  and  with  a  hand  on  each 
side  bring  the  paper  up  tightly  around  the  drum,  lapping  the-  paper  evenly  and  glu- 
ing it  down.     Note  that  the  paper  should  lap  in  the  direction  opposite  that  in  which 


38  Outlines  of  Experimental  Physiology 

the  drum  will  travel,  to  prevent  the  writing-  point  on  the  lever  from  catching  at  the 
fold. 

Blackening  the  drum.  Note  that  the  paper  is  wider  than  the  drum.  This  is  to 
prevent  smoking  the  drum  itself.  Hold  the  drum  by  the  shaft  and  turn  it  rapidly  in 
the  flame.     A  thin  brown  coating  is  much  better  than  a  thick,  black  one. 

After  blackening  the  paper,  cut  away  the  projecting  edges,  if  necessary,  with  a 
scalpel. 

To  remove  the  paper  from  the  drum.  NOTE  CAREFULLY.  The  paper  is  ex- 
tra long.  Always  cut  the  paper  from  the  drum  by  inserting  a  scalpel  between  the 
overlapping  edges.  You  thus  secure  a  clean  end  to  handle  the  tracing  by  and  also 
avoid  scratching  the  drum  itself.  Never  lay  t.he  drum  down.  Denting  or  scratch- 
ing or  other  injury  to  the  drum  must  be  paid  for. 

The  facts  demonstrated  by  each  tracing  should  be  fully  written  up  in  your 
notes.  Put  your  name  and  the  date  on  the  tracings  and  fix  them  by  passing  them 
through  a  solution  of  shellac. 

Expt.  XXIV.  Preliminary  Preparation  to  the  Study  of  the  Frog's  Cardiac 
Nerves  and  Heart  Action. 

Preparation  of  the  Vagus  Nerve.  Fasten  a  large,  formole-prepared  frog  on 
the  holder,  back  down.  Pass  a  glass  tube  through  the  eosophagus  into  the 
stomach.  Remove  the  muscles  lying  over  the  petro-hyoid  bone.  Lying  near  the 
line  between  the  angle  of  the  jaw  and  the  auricle  are  four  nerves;  first,  the  hypo- 
glossal; this  one  is  superficial.  Near  their  emergence  from  the  skull,  it  is  the 
lowest  of  the  nerves  but  later,  the  uppermost.  It  crosses  the  remaining  nerves  and 
the  blood  vessels  and  passes  forward  and  inward  toward  the  tongue:  Second,  the 
glosso-pharyngeal  which  soon  turns  forward  beneath  the  hypoglossus  parallel  to 
the  ramus  of  the  jaw;  third,  the  vagus;  and  fourth,  the  laryngeus,  the  two  lying 
almost  parallel  in  the  line  between  the  angle  of  the  jaw  and  the  auricle.  The 
laryngeus  rests  upon  the  petro-hyoid  muscle  and  passes  upward  and  inward 
beneath  the  arteries  toward  the  larnyx.  The  vagus  runs  at  first  along  the  superior 
venacava  to  the  auricle;  a  branch  is  given  oflf  to  the  lungs.  Clear  the  vagus  and 
tie  a  silk  thread  around  the  nerve.  Cut  the  nerve  on  the  central  side  of  the  liga- 
ture, so  that  the  peripheral  stump  can  be  placed  on  the  electrodes  for  stimulation. 
Divide  the  laryngeal  branch.  Note  how  near  the  vagus  goes  to  the  eustachian  tube 
and  ascertain  if  stimulation  of  the  tube  inside  the  mouth   reaches   the   vagus. 

Expt.  XXV.  Preparation  of  the  Sympathetic  Nerve.  Cut  away  the  lower  jaw 
of  a  large  frog  at  the  angle  of'the  mouth  a  short  distance  downward,  not  injurying 
the  vagus.  At  the  junction  of  the  skull  and  backbone  will  be  seen  on  each  side 
the  L.  A.  S.  muscle.  See  the  chart  for  the  explanation  of  the  parts.  OC=Occiput 
L.  A.  S.=Levator  Anguli  Scapulae.  Sym.=Sympathetic.  Gp=Glosso-pharyn- 
geal.  VS=Vago-Sympathetic.  G=Ganglion  of  the  Vagus.  Ao=Aorta.  SA= 
Subclavian  Artery. 

(a).  Expose  the  vertebral  column  where  it  joins  the  skull  and  remove  the  mucous 
lining  of  the  mouth  and  clear  away  the  connective  tissue  lying  over  the  first  cervical 
vertebra  and  the  sympathetic,  with  its  ganglion,  will  be  seen.  The  sympathetic 
is  situated  directly  beneath  tbe  L.  A.  S.  muscle,  which  must  be  carefully  removed. 
The  nerve,  usually  pigmented  and  lying  under  the  artery,  will  then  be  seen. 
Carefully  isolate  and  put  two  ligatures  around  the  nerve    as    far     as    possible  from 


Outlines  of  Experimental  Physiology  39 


the  skull  (about  the  level  of  the  larf^e  brachial  nerve).  Cut  between  the  ligatures 
and  isolate  carefully  to  its  junction  with  the  vagus  ganglion.  Note  especially 
whether  the  sympathetic  of  both  sides  can  be  stimulated  with  electrodes  placed  far 
back  in  the  mouth;  how  near  the  wires  must  be  and  how  far  back  in  the  mouth. 
Illustrate  the  connection  of  the  vagus  and  sympathetic  with  the  heart. 

[b)  With  the  prepared  frog  (n),  follow  the  directions  under  Expt.  XXVII  as  far 
as  possible,  as  a  preparation  .for  future  work. 

(c)  With  the  prepared  frog  of  (b)  follow  the  directions  under  Expt.  XXVI. 
Draw  a  dorsal  and  ventral  view  of  the  superficial  mucles  and  indicate  the  position 
of  the  sciatic  nerve  to  its   origin. 

Expt.   XXVI.   Nerve  Muscle  Preparation. 

Divide  the  body  transversely  behind  the  forelimbs.  Remove  the  viscera.  Seize 
the  spinal  column  with  the  finger  and  thumb  of  one  hand,  and  the  skin  of  the  back 
with  the  other.  Draw  the  hind  limbs  out  of  the  skin.  Cautiously  divide  the  con- 
nective tissue  between  the  semi-membranosus  and  the  biceps  femoris  and  observe 
the  sciatic  nerve  and  femoral  vessels.  Clear  the  nerve  from  the  knee  to  the  vertebral 
column,  using  scissors  and  forceps.  The  nerve  itself  should  not  be  touched  with 
the  instruments.  Divide  the  spinal  column  longitudinally  and  cut  away  all  but  a 
small  piece  of  the  bone.  (This  is  left  for  handling  the  nerve).  Pass  now  to  the 
leg.  Cut  through  the  Tendo  Achillis  of  the  Gastrocnemius  below  the  thicken- 
ing of  the  heel.  Free  the  muscle  up  to  its  origin  from  the  femur,  taking  care  not  to 
harm  the  branch  of  the  nerve  which  enters  the  muscle  on  its  posterior  surface  near 
the  knee.  Cut  through  the  tibia  about  1  cm.  from  the  knee  joint.  Clear  away 
the  muscles  from  the  lower  end  of  the  femur,  avoiding  the  sciatic  nerve.  Cut 
through  the  femur  about  its  middle.  I^ay  the  sciatic  nerve  along  the  gastrocne- 
mius muscle  for  safety.  Be  careful  not  to  stretch  the  nerve.  Keep  it  moistened  with 
normal  saline  solution. 

Expt.  XXVII.  {a).  Pith  a  frog.  Wrap  the  frog  in  a  cloth,  the  head  out.  Hold 
with  fingers  of  the  left  hand,  pressing  down  the  tip  of  the  frog's  nose  with  the  left 
fore  finger.  Pass  the  right  forefinger  along  the  middle  line  of  the  head.  A  slight 
depression  will  be  felt  at  the  junction  of  the  skull  andthe  trunk  Here  the  cerebro- 
spinal canal  has  no  bony  covering.  At  this  point  make  a  cut  li  of  an  inch  long 
through  the  skin  in  the  mid-line.  Thrust  the  blunt  needle  vertically  through  the 
soft  tissues  until  the  point  is  stopped  by  the  vertebrae.  Moving  the  point  of  the  wire 
toward  the  head,  push  it  along  the  brain  cavity,  moving  it  slightly  from  side  to  side. 
Use  a  piece  of  a  match  to  stop  the  bleeding.  Place  the  frog  on  the  table  for 
observation. 

(b).  Compare  the  reactions  with  those  of  a  normal  frog.  Pinch  different  parts. 
Place  it  on  its  back.     Conclusion  as  to  the  absence  or  presence  of  the  brain? 

Expt.  XXVIII.  Heart  Action.  Place  the  frog,  back  down,  in  the  holder;  make 
a  median  cut  1>2  inches  long,  beginning  below  the  head  Avoid  the  median  vessel. 
Then  cut  from  the  middle  of  the  incision  from  side  to  side  about  a  half  inch  Lift 
the  sternal  cartilage  doing  no  harm  to  the  deeper  part  and  cut  off  its  tip  thus  avoid- 
ing the  epigastric  vein.  Divide  the  abdominal  muscles  from  side  to  side  in  the  line  of 
the  cross  cut.  Open  the  pericardium,  turn  the  frog-holder  over  to  the  right  nearly 
perpendicular  thus  bringing  the  frog's  left  side  next  the  table      Support  the  holder 


40  Outlines  of  Experimental  Physiology 

with  the  pahii  of  the  left  hand.  With  the  forceps  in  the  other  hand  pull  aside  the 
chest  wall  so  as  to  expose  the  heart,  {a).  Observe  the  great  veins,  auricles,  ven. 
tricles,  and  bulbus  are  contracting.  The  aortae  are  not.  The  veins  first,  then  the 
auricles,  ventricles  and  bulbus  contract.  Note  the  color  of  the  contracting  ventricle. 
Make  and  label  an  enlarged  drawing  of  both  the  dorsal  and  ventral  surfaces  of  the 
heart,  showing  the  vagus  and  other  nerves  near  the  heart,  (Ecker,  p.  212.  Schenck 
p.  279).  In  the  frog,  the  augmentor  and  inhibitory  nerves  reach  the  heart  through 
the  splanchnic  branch  of  the  vagus.  To  excite  either  fibre  alone,  it  is  necessary  to 
stimulate  the  respective  nerves  above  their  junction. 

ib).  Place  the  heart  in  the  heart-holder  having  its  lever,  weights,  and  moisten- 
ed filter  paper  in  place.  Arrange  a  time-marker  for  marking  seconds  on  a  drum 
revolving  so  that  the  beats  shall  appear  far  enough  apart  to  be  readily  counted. 
Bring  the  writing  point  of  the  lever  and  that  of  the  time-marker  vertically  under 
each  other  on  the  surface  of  the  drum.  When  the  lever  rests  on  the  auriculo- 
ventricular  junction,  the  tracing  shows  the  systole  of  both. 

For  simultaneous  records  of  auricular  and  ventricular  contraction,  special 
levers  are  put  both  on  the  auricles  and  ventricle. 

(a).     Which  parts  of  the  curve  trace  the  systole  and  which  the  diastole? 

(h).     Which  is  Iwnger,  and  how  much? 

(c).     What  is  the  rate  per  minute? 

Expt.  XXIX.  Action  of  the  Vagus  on  the  Heart.  (See  Musken,  Am.  Jour,  of 
Phys.  Vol.  1.  p.  486  ).  Arrange  the  inductorium  for  weak  tetanizing  currents.  In 
the  primary  circuit  place  the  electro-magnetic  signal.  Expose  the  heart,  place  in  a 
heart-holder.  Let  the  point  of  the  lever  write  exactly  above  the  signal  on  a  drum 
revolving  so  slowly  that  the  individual  beats  shall  appear  in  the  curve  very  close 
together  and  yet  far  enough  apart  to  be  counted.  Lay  the  vagus  nerve  on  the  elect- 
rodes (or  use  Musken's  Vagus  Stimulators  placed  just  posterior  to  the  inner  opening 
of  the  Eustachian  tube,  pressing  the  electrodes  firmly  against  the  mucous  lining  of 
the  dorsal  side  of  the  roof  of  the  mouth).  Start  the  drum.  As  soon  as  good 
curves  are  writing,  start  the  inductorium  and  open  the  short  circuiting  key  for  about 
20  sec.  The  heart  will  be  inhibited.  Note  that  the  arrested  heart  is  always  re- 
laxed; i.  e.,  in  diastole.  The  latent  period  is  short  (one  or  two  heart  beats).  A 
brief  after  effect  is  present.  If  the  stimulous  is  continued,  the  heart  will  begin  to 
beat  even  during  stimulation,  showing  that  the  inhibitory  mechanism  can  be  ex- 
hausted. The  heart  beats  more  rapidlj'  and  usnally  more  strongly  immediately 
after  inhibition  than  before.  This  probably  is  due  to  the  after  effect  of  the  stimula- 
tion of  the  augmentor  fibres  in  the  vagus  trunk.  Repeat  the  stimulation  but  weak- 
en the  current  by  moving  the  secondary  farther  from  the  primary  coil.  With  a 
suitable  strength  of  current,  the  heart  will  be  slowed  but  not  arrested.  The  dura- 
tion of  diastole  will  be  less,  while  the  duration  of  the  systole  will  be  changed  but 
little,  if  at  all.  A  stronger  excitation  would  lengthen  both  systole  and  diastole. 
The  diminution  in  force  appears  before  the  diminution  in  frequency.  Compare  the 
curves  obtained  before,  during,  and  after  stimulation. 

(b).  Action  of  the  vSympathetic  on  the  Heart.  Arrange  the  apparatus  as  in  (a). 
Prepare  the  sympathetic  as  previously  directed  (or  use  Musken's  electrodes  placing 
the  lead  points  close  against  the  sides  of  the  vertebral  column,  just  posterior  to  the 
roof  of  the  mouth).     Expose  the  heai-t.     Place  it  in  the  holder.     Obtain  a  curve,  then 


Outlines  of  Experimental  Physiology  41 

stimulate,  the  sig'tial  indicating- the  duration  period  of  the  stimulation,  then  obtain 
a  curve  after  stimulation  Compare  the  frequency  and  force  of  the  heart's  action  as 
indicated  by  the  curves. 

Expt.  XXX.   The  Influence  of  the  Sciatic  on  the  Heart  and  Blood-vessels. 

(«)•  Destroy  the  frog's  brain  in  front  of  the  medulla.  Expose  the  sciatic, 
insulate  with  rubber,  ligate  half  a  centimeter  apart  Place  the  heart  in  the  holder, 
obtain  curves,  then  cut  between  the  ligatures.  Obtain  a  curve  while  stimulating 
the  peripheral   and  again  after  stimulating  the  central  end.     Compare. 

{0)  Examine  the  circulation  in  the  frog's  web  under  the  microscope.  Note  care- 
fully all  the  changes  produced  in  the  vessels  during  stimulation  of  the  peripheral 
end  of  the  sciatic.     Has  stimulation  of  the  central  end  any   effect? 

Sounds  of  the  Heart. 

Expt.  XXXI.  (a)  Study  the  cardiac  impulse  in  a  fellow  student,  first  by  direct 
auscultation,  then  with 

{f>)  The  Stethoscope  or  Phonendoscope.  Make  out  the  sounds  and  pauses. 
Which  sound  is  most  distinct  in  this  region? 

(c)  With  the  hand  over  the  radial  artery,  determine  whether  the  pulse  is  felt 
in  the  period  of  pause  or  sound. 

{d)  Place  the  stethoscope  over  the  junction  of  the  second  rib  with  the  sternum 
on  the  right  side.  Compare  the  relative  intensity  of  the  sounds  of  the  heart  here 
with  the  relative  intensity  a.%  heard  over  the  cardiac  impulse  or  other  regions. 

Expt.  XXXII.   Time  of  Systolic  Phase. 

Arrange  a  tuning  fork  (100  vibrations  per  second)  and  a  signal  to  write  on  the 
drum.  Then  with  the  stethoscope,  listen  for  the  first  and  second  sounds,  closing 
the  key  for  each.  Calculate  the  time  for  several  observations  and  take  the  mean. 
Calculate  the  time  for  diastole  and  pause.     For  systole. 

Expt.   XXXIII.   Human  Pressure   Pulse. 

Frequency:— Palpate  the  pulse  with  ball  of  first,  second,  and  third  fingers. 
With  the  touch  alone  you  can  learn  the  rate,  rhythm,  volume,  strength,  and  com- 
pressibility. 

(a).  Note  the  frequency  per  minute  when  the  subject  is  standing,  sitting,  lying 
down  and  after  exercise.  A  pulse  which  is  obliterated  by  slight  pressure  is  termed 
"soft".     If  considerable  pressure  is  required  is  "hard". 

(b).  With  a  sphygmomanometer  compare  the  pulse  with  the  blood  pressure  in  a 
student  in  different  attitudes. 

Expt.  XXXIV.     Carotid  Pulse  or  Cardiogram. 

Place  the  button  of  the  cardiograph  over  the  cardiac  impulse;  or  the  thistle  tube 
without  a  membrane  joined  to  a  delicate  tambour  (side  branch  open  until  adjusted) 
over  the  carotid  artery,  then  close  the  side  branch  of  the  tambour.  Obtain  tracings, 
calculate  the  frequency  and  compare  with  the  form  and  frequency  of  curves  obtained 
when  standing,  sitting  and  after  exercising. 


42  Outlines  of  Experimental  Physiology 


Expt.  XXXV.     Radial  Pulse. 

(a).  Cover  the  small  thistle  tube  with  a  rubber  membrane  having-  a  small  cork 
cemented  to  its  centre.  Place  the  cork  on  the  radial  artery  and  record  throug-h  the 
tambour  a  radial  pulse.  In  order  to  secure  a  satisfactory  curve  the  deg-ree  of  pres- 
sure must  be  carefully  regulated.  The  pulse  curve  gives  only  the  variations  in 
blood-pressure  and  form  of  the  pulse,  (does  not  give  absolute  blood-pressure 
— hardness,  amplitude  or  size).     These  are  better  obtained  by  palpating  fingers. 

(b)  Sphj'gmograph  Tracing.  Let  the  subject  stand  at  the  right  of  the  observer' 
resting  the  dorsal  surface  of  the  left  arm  upon  the  observer's  knee.  The  observer 
standing  with  his  right  foot  on  a  chair.  Mark  with  pencil  the  location  of  the  radial 
artery  and  adjust  the  sphj'gmograph  so  that  its  pad  is  in  position  and  the  tension 
and  pressure  adjusted  for  maximum  swing  of  the  tracing  needle  bj'  means  of  the 
pressure  screw.  Observe  whether  there  are  variations  among  the  members  of  the 
class  in  the  location  of  the  radial  artery  and-  whether  adipose  or  muscular  tissue 
hinder  the  observations  of  the  pulse.  (1).  Obtain  the  pulse  rate,  (2).,  the  pulse 
curve  when  standing,  (3).,  sitting,  (4).,  lying,  (5).,  after  exercise,  (6).,  after  inhaling 
two  drops  (on  no  account  more)  of  the  nitrite  of  amyl  on  a  handkerchief.  Observe  as 
the  face  flushes  the  pulse  will  be  softer.  (7).  Effect  of  the  vertical  position  of  the 
arm,  (8)  ,  compressing  the  arteries  at  the  elbow.  (9).  Inhale  some  ether.  Get  the 
pulse  before  and  after  smoking. 

Expt.  XXXVI.  Pulse  Volume.  Connect  the  Plethysmograph  through  a  tam- 
bour, side  tube  open,  to  write  the  variations  of  air  pressure  on  a  drum.  Obtain  a 
time  record  under  the  pulse  record  of  the  finger  inserted  not  to  impede  the  circula- 
tion in  the  plethysmograph.  (a),  horizontal  and  (b)  vertical  position  and  {c)  effect  of 
forced  respiration  upon  the  curve. 

Expt.  XXXVII.     Effect  of  Drugs  upon  the  Heart's  Action. 

(1).  Intracardiac  Inhibitory  Mechanism.  Expose  a  frog's  heart.  Note  the 
white  crescent  between  the  sinus  venosus  and  the  right  auricle.  Arrange  an  induc- 
torium  for  weak  tetanizing  currents  and  put  the  points  of  the  electrode  on  the  cres- 
cent; stimulate.     After  one  or  two  beats  the  heart  will  stop. 

(2).  Action  of  Muscarine.  Expose  the  heart  of  a  pithed  frog  in  a  heart-holder. 
Test  the  action  of  the  vagus,  either  with  Musken's  or  with  ordinary  electrodes.  Get 
a  curve,  then  with  a  clean  pipette  put  a  few  drops  of  0.1  per  cent  muscarine  on  the 
ventricle,  (b).,  a  0.5  per  cent,  (c).,  again  stimulate  the  vagus.      Result? 

(3).  (a).  Atropin  O.S  per  cent,  a  few  drops  placed  on  the  ventricle  with  a  clean 
pipette.  Get  a  curve  before  and  after  applying  the  drug.  [b).  Stimulate  the  vagus; 
what  is  the  effect?  (c).  Stimulate  the  crescent;  effect?  Upon  what  part  does 
atropin  act? 

Expt.  XXXVIII.  Nicotine.  Apply  0.1  per  cent  solution  of  nicotine  to  the  ven- 
tricle,    After  a  few  minutes,  stimulate  the  vagus  nerve.     The  heart  is  not  inhibited. 

(b).  Now  lift  the  heart  with  a  glass  rod  and  stimulate  the  intracardiac  inhibitory 
centres.  The  heart  is  inhibited.  Nicotine  paralysis  some  inhibitory  mechanism 
between  the  vague  and  the  intracardiac  nerves.  It  is  known  that  nicotine  does  not 
paralyze  nerve-trunks,  hence  it  is  probable  that  the  cardiac  inhibitory  fibres  do  not 
pass  to  the  cardiac  muscle  directly,  but  end  in  contact  with  nerve   cells   which  take 


Outlines  of  Experimental  Physiology  43 

up  the  impulse  and  transmit  it  throug-h  their  processes  to   the  muscular  fibres  of  the 
heart. 

(t).     Repeat  with  0.5  per  cent  Nicotine. 

Expt.  XXXIX.   Reflex  inhibition  of  the  heart.      (Use  a  small  frog). 

In  a  very  lightly  etherized  frog,  expose  the  pericardium  by  cutting  away  the 
chest  wall  over  the  heart.  Count  the  number  of  beats  in  periods  of  20  sec.  Con- 
tinue the  heart  count  while  an  assistant  strikes  gentle  blows  with  the  handle  of  a 
scalpel  upon  the  abdomen  at  the  rate  of  about  140  per  minute.  The  frequencj-  will 
usually  diminish;  and  in  favorable  cases,  the  heart  will  at  length  be  arrested. 
Note  the  effect  on  respiration.  Cut  both  vagi  and  repeat  the  experiment.  The 
reflex  inhibition  of  the  heart  cannot  be  secured.  It  has  been  shown  by  Bernstein 
that  the  afferent  nerves  in  this  experiment  are  the  abdominal  branches  of  the  sj'm- 
pathetic  nerve.  The  stimulation  of  the  central  end  of  the  abdominal  sympathetic 
in  the  rabbit  also  produces  reflex  inhibition  of  the  heart. 

Expt.  XL.  Digitalin.  (The  commercial  varies  in  composition,  decomposes  soon, 
and  is  soluble,  one  part  in  three  of  water). 

(a)  Pith  a  frog,  expose  the  heart,  obtain  a  normal  curve,  and  note  the  size  of 
the  auricles  and  ventricle.  Appl}^  4  gtt.  of  tincture  of  digitalis  to  the  heart.  How 
quickly-  does  it  affect  the  heart?  Which  part  contracts  more  vigorouslj-?  Is  the 
tonus  of  the  muscle  increased?  Is  the  size  of  the  ventricle?  What  is  the  change  in 
heart  curve? 

{b).  Digitalis  acts  on  the  vascular  sj'stem,  central  nervous  sj'stem  and  increas- 
es the  irritability  of  the  heart  muscle.  Fasten  a  pithed  frog  on  the  cork  board  and 
stretch  the  tongue  or  web  over  the  cover-glass  that  is  secured  over  a  hole  in  the  cork 
by  means  of  sealing  wax.  Focvis  the  microscope  on  a  certain  arteriole  and  measure 
its  diameter  with  an  e\'e-piece  micrometer.  Measure  the  diameters  of  the  heart  and 
make  drawings  of  the  same.  Now  inject  into  the  dorsal  lymph  spaces,  3  gtt.  of  Tr. 
of  Digitalis  and  measure  the  arteriole  at  intervals  of  10  minutes.  Keep  moist  with 
normal  saline  solution.  (Digitaline,  3gtt.  of  0.5  per  cent  maj'  be  used  instead  of 
tincture  ) 

(«).     What  change  occurs  in  the  diameter  of  the  arteriole? 

(b).     What  effect  would  you  expect  this  to  have  on  arterial  pressure? 

{c).  Would  its  action  on  the  arteriole  help  to  account  for  its  effect  on  arterial 
pressure? 

Expt.  XLI.     Morphine  is  eight  times  stronger  than  opium. 

Ascertain  (when  the  frog  is  quiet  against  the  side  of  a  glass  dish,)  the  rate  of  re- 
spiration, and,  if  possible,  also  of  the  heart  action,  and  the  size  of  the  pupil. 

Opium  acts  on  the  central  nervous  S3-stem.  Inject  4  drops  of  a  0.5  per  cent  solu- 
tion under  the  skin  of  a  frog.  Note  the  effect  on  the  movements — clumsj'  and  awk- 
ward. Place  in  an  awkward  position;  note  the  results.  Compare  the  reflexes  with 
those  of  a  normal  frog.  (Reflexes  are  decreased  for  perhaps  an  hour  and  then  much 
increased).  Study  the  effect  on  respiration.  Note  the  heart  action  (slow  and  weak 
when  a  large  dose  is  given)  and  change  in  the  pupil. 

Expt.  XLII.  Pith  the  frog,  note  the  size  of  a  special  bloodvessel  in  the  mesen- 
tery placed  under  the  microscope  and  micrometer  scale.  Place  a  drop  of  1  per  cent 
Suprarenal  Extract  over  the  vessel.     Note  the  effect. 


44  Outlines  of  Experimental  Physiology 

(b).  Get  a  heart  curve.  Adda  few  drops  of  a  1  per  cent  Suprarenal  Extract. 
Ag-ain  obtain  a  curve.     Note  the  effect  on  the  heart's  action. 

(c).  Thoroug-hly  wash  off  the  Suprarenal  Extract  from  the  heart.  Obtain  a 
cardiac  curve.  Put  two  drops  of  33  per  cent  alcohol  on  the  heart.  Note  the  first 
and  later  effects.  (Alcohol  evaporates).  If  the  heart  ceases  to  beat  stimulate  with 
the  electrical  current.     The  effects  vary  with  the  dose. 

Expt.  XLIII.  Effect  of  Physostig-ma.  Pith  a  frog  or  a  curarized  frog  may  be 
used.  Physostigma  acts  on  the  central  nervous  system,  heart  respiration,  muscles 
and  e3'e.  Obtain  a  muscarin  curve  both  before  and  after  phj'sostigma.  Expose  the 
heart;  apply  a  drop  of  phj^sosligma;  obtain  a  curve.  The  drug  slows  the  heart  but 
increases  the  irritability  of  heart  muscle,  so  that  vagus  stimulation  has  little  effect. 
Muscarine  slowing  is  abolished  because  the  muscle  is  more  irritable,  not  because 
the  nerve  endings  are  affected. 

Expt.  XLIV.  Action  of  Aconite.  Obtain  a  heart  curve  from  a  normal  frog. 
Inject  two  drops  of  tincture  of  aconite.  Obtain  curves  at  intervals  of  from  5  to  30 
minutes. 

(i>).  Take  a  sphygmographic  tracing  from  a  student.  Note  the  pulse.  Ad- 
minister by  mouth  0.2  c.c.  tincture  of  aconite  and  0.06  c.c.  every  10  minutes  until  the 
action  on  the  pulse  is  noticeable.  Count  the  pulse  at  short  intervals.  How  is  the 
heart  rate  affected  ?     What  subjective  sensations  are  produced  ? 

Expt.  XLV.  Transfusion  of  Salt  Solutions  through  the  Turtle's  or  Frog's 
Heart.     (Walden,  Am.  Jour.  Phys   Vol.  III.     Howell,  Amer.  Jour.  Phys.) 

Ligate  or  break  the  turtle's  neck  or  pith  the  frog,  fasten  it  back  down  in  the 
holder,  expose  the  heart  and  proximal  vessels,  ligate  all  vessels  except  the  post  cava 
and  left  aorta.  Into  the  aorta,  tie  a  canula  with  a  rubber  tube  attached,  pushed 
partly  into  the  ventricle  for  an  outflow  tube.  Connect  a  canula  with  the  post  cava 
or  tie  it  into  the  right  auricle  for  an  inflow  tube;  join  to  this  aT  tube  connected  with 
the  bottle  or  burette  of  solutions.  Fasten  the  tip  of  the  ventricle  by  a  silk  thread  to 
a  recording  lever  or  use  the  lever  with  the  heart  holder  for  curves.  Remove  the  clot 
from  the  heart. 

(a).     Irrigate  with  0.7  per  cent  NaCl  everj^  ten  min.utes  until  the  heart  slows. 

(b).  Irrigate  with  100  c.c.  0.7  per  cent  NaCl  plus  a  few  drops  of  1  per  cent 
CaClg  everj^  five  minutes.  Continue  to  add  until  6  c.c.  CaCl2  have  been  added. 
Obtain  curves  to  show  the  effect  of  the.CaCls- 

(c}.  After  half  an  hour  or  so,  if  the  heart  beats  feebly  add  100  c.c.  NaCl  0.7  per 
cent;  2.3  c.c.  CaClg,  1  per  cent;  1.5  c.c.  KCl,  1  per  cent.     Effect  ? 

(d).  After  about  half  an  hour,  if  the  heart  beats  feebly,  irrigate  with  milk 
diluted  with  nine  volumes  of  0.7  per  cent  NaCl. 

(e).  If  the  heart  beats  feebly  after  an  hour  or  less,  revive  with  100  c.c.  NaCl, 
0.7  per  cent;  2.3  c.c.  CaCls,  1  per  cent;  1.5  c.c.  KCl,  1  per  cent;  0.6  c.c.  Na2C03, 
1  per  cent.     What  is  the  effect? 

What  are  your  conclusions  regarding  proteid  and  inorganic  salts  on  the  heart 
action?     {Milk  contains  certain  salts). 

Expt   XLVI.     Action  of  Inorganic  Salts  upon  the  Heart. 

Sever  a  ring  about  three  mm.  wide,  parallel  with  the  auricular-ventricul  'fur- 
row, from  the  ventricle  of  the  turtle  or  frog.     Put  on  two   ligatures    with   loops  close 


Outlines  of  Experimental  Physiology  45 

tog-ether  and  divide  the  ring-  between  them.  Fasten  one  loop  on  the  strip  to  the  bent 
end  of  a  small  canula  in  a  g^lass  tube  made  especially  for  the  purpose;  and  the  other 
end,  with  its  loop  to  an  inverted  counterpoise  lever  arrang'ed  to  record  on  a  slowly 
moving- drum.  Immerse  in  a  0.7  per  cent  NaCl  solution  in  the  g-1  ass  tube  provided 
with  a  rubber  outflow  tube.  Have  a  dish  ready  for  the  solution.  Protect  the  tube 
with  a  cap  of  oiled  paper  or  rubber  tissue.  After  a  latent  period,  the  contractions 
soon  reach  a  maximum  and  then  die  away.  Sodium  cannot  maintain  continued 
activitj'.  It  diminishes  the  tonus.  Gradually  add,  drop  by  drop,  a  solution  of  1 
per  cent  CaCls".  This  is  isotonic  with  0.7  per  cent  NaCl.  Is  a  chang-e  noted?  Con- 
tractions may  cease  in  NaCl  but  Ca  added  will  leng-then  the  period  during  which 
the  muscle  will  contract.     Calcium  increases  the  tonus. 

(a).  Put  the  muscle  in  NaCl  0.7  per  cent  again,  if  it  still  contracts.  Add 
gradually  KCl  0.9  per  cent  until  a  change  is  evident. 

(b).  Potassium  chloride  0.9  per  cent  is  approximately  isotonic  with  0.7  per  cent 
NaCl.     Potassium  causes  all  contractions  to  cease. 

(c).  Modified  Ringer  Solution.  100  c.  c.  NaCl,  0.7  per  cent;  3.5  c.  c.  CaClg, 
1  per  cent;  2.8  c.  c  KCl,  0.9  per  cent).  Long  continued  contractions  of  the  tortoise 
strips  will  be  secured.  Rhythmical  contractions  may  be  due  to  chemico-phj'sical 
stimulus  of  inorganic  salts  in  the  blood  being  present  in  definite  proportions.  Most 
observers  are  agreed  that  the  inert  action  of  these  salts  is  essential.  The  sinus  may 
be  the  more  sensitive  to  the  chemical  stimulus. 

(ci).     Influence  of  Temperature  on  Frequency  of  Contractions. 

Get  a  normal  curve  With  a  pipette,  put  on  NaCl  at  30  °C.  Fill  the  spoon  of 
the  holder.  Replace  with  NaCl  at  5  ^C.  Note  the  difi'erence  in  the  curves.  This 
can  be  tried  either  on  the  heart  directly  or  on  the  strips  of  the  ventricle.  (Greene, 
Am.  Jour.  Phj's.). 

Expt  XLVII.  Have  ready  the  foUovviug.  M/8  NaCl;  M4  Cane  sugar;  90  c.  c. 
M/8  NaCl  plus  10  c.  c.  M/8  CaClo. 

(a).     Put  the  ventricular  strip  in  M/8  NaCl.     Try  sodium  citrate,  also. 

{b).     When  the  strip  is  beating  in  (a),  put  it  into  M/8  cane  sugar. 

(c).     Return  the  strip  to  M/  NaCl.     Do  the  beats  return  or  change? 

(d).  When  NaCl  acts  toxic,  put  the  strip  into  the  NaCl  plus  CaClo  solution. 
Effect? 

Expt.  XLVIII.     Lingle's  Experiment 

(a).  Non-conductors.  M  4^ Cane  sugar  is  equal  to  M/8  NaCl  (No  beats).  Prove 
that  the  strip  is  not  killed  by  putting  it  into  an    electrolyte. 

(b).     In  NaCl  M/8,  after  one  hour,  it  beat  for  1-3  hours. 

(c).     Number    of    Ions.  40c.c.    M /4     cane    sugar    plus    10  c  c.    M/s  NaCl 

gives  beats. 

{d).     NaBf  yi/i  gives  stronger  beats  than  'M.^   NaCl. 

(effect  of  too  many  ions).  After  a  NaCl  standstill  for  H  hour,  put  it  into 
M/^  cane  sugar.     It  beats  again. 

(f).  CaClgM/,  no  beats.  Remove  the  excess  of  Ca  bj-^  putting  it  in  M/^  NaCl. 
The  beats  are  resumed. 

iS").     48  c.  c.  M/s  NaCl  plus  2  c.  c.  M4  CaClj.     It  beats  but 
'^7  c.  c.  M/8  LiCl  plus  3  c.  c    M  -8  CaCl2,  does  not  beat. 
48  c.  c.  M/s  NaCl  plus  0.003  KCl,  loss  of  tone. 

{k).     KCl  M/8,  no  beat.  , 

Lingle,  Am.  Jour.  Phys. 


( 


46  Outlines  of  Experimental  Physiology 


Expt.  XLIX.  Action  of  Strychnine.  Pith  a  frog".  (The  brain  inhibits 
spasms).  Ligate  the  thig-h,  except  the  sciatic  nerve,  at  its  junction  with  the  body. 
Be  sure  to  protect  from  drying-.  Turn  the  frog-  over  and  make  a  long-itudinal  incision 
to  one  side  of  the  median  line,  about  one  inch  long,  on  the  unligatured  side.  Press- 
ing- aside  the  viscera,  pick  up  the  sacral  plexus  of  nerves  going  to  the  uninjured  leg. 
The  sacral  plexus  may  be  readily  recognized  lying  on  either  side  of  the  median  line. 
Pass  a  thread  around  the  nerves  loosely,  so  as  to  quickly  find  them  when  wanted. 
Inject  into  the  dorsal  lymph  sac  one  or  two  drops  of  0.8  per  cent  strychnine. 

(a).  What  part  of  the  frog  is  reached  by  the  poison?  What  part  is  protected 
from  it?     Illustrate  by  a  diagram. 

(6).  If  strychnine  acted  upon  the  central  nervous  system,  would  the  legs  be 
equally  convulsed?  If  it  acted  on  the  cord?  If  it  acted  on  the  motor  nerves?  On  the 
muscles  directly?     Are  both  legs  convulsed?     Are  the  sensory  nerves  affected? 

(c).     To  what  parts  of  the  reflex  arc  have  you  limited  the  action  of  the  strychnine? 

B.  Using  as  a  guide  the  thread  formerly  passed  around  the  sacral  plexus  pick 
it  up,  tie,  and  sever  it  between  the  two  ligatures  on  the  uninjured  side. 

(a).     Does  the  strychnine  reach  the  motor  nerves  and  muscles  of  the   uninjured 

leg? 

(b).  If  strychnine  were  a  convulsant  through  its  action  on  either  the  motor 
nerves  or  the  muscles,  or  both,  would  the  injured  leg  still  participate  in  the  convul- 
sions? 

(c)  Demonstrate  that  the  muscles,  sciatic,  and  sacral  plexus  below  the  point 
at  which  it  was  severed,  are  still  intact,  by  stimulating  the  distal  portion  of  the 
sciatic. 

(d).  To  what  elements  of  the  reflex  arc  have  3'^ou  limited  the  possible  action  of 
the  strychnine? 

C.  Expose  the  heart  of  a  small  frog  and  ligate  the  aortae  at  the  base.  With 
an  aneurism  needle  pass  a  fine  thread  around  the  aortae,  taking  care  not  to  injure 
the  auricles,  and  ligate.  With  a  scalpel,  cut  through  the  occipito  alantoid  mem- 
brane and  bend  the  head  forward.  Remove  the  posterior  wall  of  the  upper  end  of 
the  spinal  canal  by  inserting  the  smaller  blade  of  strong  scissors  into  the  spinal 
canal  and  cutting;  taking  care  not  to  injure  the  spinal  cord.  Allow  a  drop  of  the 
solution  of  strychnine  to  fall  directly  upon  the  cord,  or  with  a  fine  hypodermic  need- 
le, inject  two  drops  (not  more)  into  the  arachnoid  space. 

(a).     What  effect  has  ligation  of  the  aortae  upon  the  circulation? 

(b).  Would  stoppage  of  the  circulation  prevent  the  drug  from  reaching  the  peri- 
pheral terminations  or  trunks  of  the  sensory  nerves?     Motor   nerves?     Muscles? 

(c).     Where,  then,  must  the  strychnine  act  to  produce  the  observed    symptoms? 

(d).  Would  cessation  of  the  circulation  delay  the  action  of  the  strychnine  on 
the  cord  by  slowing  the  rate  of  absorption  by  the  latter? 

D.  After  observing  the  results  in  Expt.  C  destroy,  first,  the  upper,  then  the 
lower  portions  of  the  cord,  by  passing  a  wire  down  the  spinal  canal. 

(c).     Do  the  results  agree  with  those  of  the  previous   experiments? 
Note.     Destruction  of  the  upper  part  of  the  cord  may  take  place  during  the    pre- 
paration of  the  animal.     If  so,  the  upper  limbs  will  not  take  part  in  the  convulsions. 

Expt.  L.     Independent  Irritability  of  Muscle  and  the  Influence  of  Curare. 
Prepare  the  frog  as  for  the  strychnine  experiment,  with  the  important  difference 
that  the  sciatic  plexus  is  not  exposed  in  this  experiment.     Inject  a  few  drops  of  a   1 


Outlines  of  Experimental  Physiology  47 


per  cent  curare,  into  a  Ij-mph  sac.  Test  the  reflex,  soon  the  leg  from  which 
the  poison  is  excluded  still  respond  to  the  stimulus  of  its  own  foot  as  well  as  to 
strong  stimulus  of  the  other  What  paths  therefore,  are  still  functional?  Wh^n 
all  reflexes  except  in  the  ligatured  limb  have  ceased,  (a),  stimulate  the  sciatic  be- 
low the  ligatured  area.  There  will  be  no  contraction.  (If.  Stimulate  above  the 
ligatured  area  and  also  the  sciatic  of  the  unligatured  leg  supplied  with   poison. 

ic).  Stimulate  the  muscle  directly  of  both  legs.  What  structure  has  curare 
paral3'zed?  Can  muscle  contract  without  the  agencj'  of  nerves?  Have  you  proved 
that  curare  does  not  affect  the  cord,  the  nerve  trunks,  afferent  nerve  fibres,  or  heart 
action?     Why  should  curare  not  be  emplo3'ed  as  £in  anaesthic? 

Expt.  LI.     Production  and  Inhibition  of  Muscular  Twitchings. 

Normal  frog.  Notice  posture,  coordination,  respiration,  (1,  rate,  2.  mode)  and 
reflexes. 

Inject  into  the  Ij-mph  sac  of  an  unpithed  frog  2,'^  c  c.  of  M/8  sodium  citrate. 
Notice  carefulh-  all  changes  which  take  place.  Do  any  parts  of  the  body  show 
tremors  or  tetanus?     If  so,  where  and  to  what  extent? 

When  the  tremors  become  well  established,  inject  1}4  c.  c.  M/^CaCls-  Note  ef" 
feet.  Compare  in  every  point  your  results  with  those  of  other.  Note  the  heart  ac- 
tion, respiration,  and  reflexes  after  '2  hour. 

Make  j-our  observations  carefully'. 

(a)  How  does  the  destruction  of  the  upper  part  of  the  cord  effect  the  convul- 
sions? 

(b).  What  is  the  effect  on  the  entire  cord?  Does  reflex  still  j>ersist?  Does 
stimulation  of  the  muscle  or  sciatic,  directly,  give  a  response? 

Expt.  LII.   Influence  of  Veratrine. 

Prepare  a  frog  as  for  curare  experiment.  Inject  5  drops  of  0.1  per  cent.  Vera- 
trine into  a  dorsal  Ij-mph  sac.  Notice  the  behavior  of  the  muscles  during  and 
after  a  jump,  heart  action,  respiration  and  reflexes.  Stimulate  the  ligatured,  then 
the  other  leg  and  muscle  directly.  Sever  the  sacral  plexus.  Has  the  duration  of  the 
contraction  of  its  muscle  been  altered? 

To  what  element  in  the  reflex  arc  have  j'ou  limited  its  action? 

(b).  Remove  the  lower  jaw  to  the  hyoid.  Drop  0.1  per  cent  Veratrine  on  either 
the  hv'oglossus,  gastrocnemius  or  sartorius  fastened  to  a  clamp  and  muscle  lever. 
Record  the  direct  stimulation  of  a  few  contractions  on  a  slowly  moving  drum, 
and  compare  the  curves  with  normal  ones  obtained  from  the  same  kind  of  muscle. 

Expt.  LIII.  Arterial  blood   pressure, 

A  preliminary  operation  on  the  Carotid,  Superior  laryngeal.  Phrenic,  Depress- 
or, Sympathetic.  -Sciatic,  and  Femoral.  These  dissections  are  performed  on 
dead  animals  as  a  preparation  for  the  work.  Be  sure  to  take  notes  on  the  effect 
of  the  anaesthetic. 

Anaesthetize  a  cat  or  rabbit  with  either.  (For  a  dog,  use  a  hypodermic  injec- 
tion of  2  per  cent  Morph.  Hydrochlor;  for  large  dog,  about  8c.  c.  or  1  c  c.  per  kilo 
of  body  weight,  or  use  chloratone,  C4  H^  O  CI3,  dose  0.2  gram  per  kilo.  The  dog 
will  anaesthetize  for  hours.  Given  in  warm  aqueous  solutions  per  mouth.  Pulse 
slightly  lowered.  Little  effect  on  blood  pressure.  Put  the  animal  in  a  holder, 
moisten  and  clip  hair    from     the    part    to  be  operated  upon.     Make  a    longitudinal 


48  Outlines  of  Experimental  Physiology 

median  incision  one  and  one-half  inches  long-,  just  posterior  to  the  larnyx.  The 
skin,  muscles  and  fascia  are.  thus  cut  and  the  sterno-hyoid  and  sterno-mastoid  are 
exposed  The  thin  narrow  sterno-thyroid  lies  below  the  sterno-hyoid,  inserted  to 
the  th3'roid  cartilages.  The  thyroid  g-lands  are  latero-posterior  to  the  larynx. 
Loosen  the  skin  from  the  muscle  with  the  handle  of  the  scalpel  and  hook  apart  with 
weights.  Note  the  large  external  jugular  just  under  the  skin  at  the  external  edge 
of  the  sterno-mastoid  extending  across  it.  Separate  the  two  muscles  and,  in  the 
dog,  you  will  find  the  carotid;  vagus,  and  internal  jugular,  surrounded  by  the 
cervical  facia  or  common  sheath  In  the  cat  and  rabbit  the  vagus  and  sympathetic 
run  a  separate  course.  The  vagus  is  external  to  the  carotid  and  internal  to  the 
jugular.  Isolate  the  carotid  and  vagus  on  both  sides,  the  crural  nerve,  exteral 
jugular  or  femoral  vein,  and  the  superior  laryngeal  of  one  side. 

(a).  Inserting  the  Canula.  Select  a  proper"  sized  T  canula  fitted  with  rubber- 
tubing,  the  latter  clamped;  the  right-angled  end  is  connected  to  a  manometer.  Iso- 
late an  inch  of  the  carotid  and  pass  two  ligatures  around  it.  Tie  the  ligature  that 
is  farthest  from  the  heart  and  clamp  the  carotid  about  an  inch  below  it  with  bull- 
dog forceps.  Now  make  a  V  shaped  incision  in  the  part  of  the  carotid  that  is  isolated. 
Use  sharp  scissors  and  cut  through  only  Yj,  of  the  circumference  of  the  vessel.  By 
means  of  a  seeker,  insert  the  canula,  trying  it  with  the  second  ligature.  When 
ready  for  the  blood,  remove  the  clamps  from  the  carotid  and  tubing.  Don't  forget  to 
have  the  beaker  ready  and  graduated  for  hemorrhage. 

(b).  The  superior  laryngeal  branch  of  the  vagus  arises  far  forward  beyond  the 
anterior  end  of  the  larynx.  At  its  origin  from  the  vagus  is  an  enlargement  of  the 
nerve  known  as  the  ganglion  of  the  trunk.  Trace  the  superior  laryngeal, 
to  the  larynx  which  it  enters.  It  anastomoses  with  the  inferior  laryngeal  by  a 
branch  passing  beneath  the  wing  of  the  thyroid  cartilage.  Somewhat  posterior  to 
the  origin  of  the  superior  laryngeal,  the  sympathetic  trunk  separate  from  the  vagus 
until  it  ends  in  the  superior  cervical  ganglion. 

[c).  The  phrenic  branches  from  the  4th,  5th,  and  6th  cervical  nerves,  unite  near 
the  first  rib  to  form  this  trunk.  It  passes  mesial  to  the  sternal  artery  and  dorsal  to 
the  brachial  artery  into  the  thorax.  The  right  rests  on  the  lateral  aspect  of  the 
pre  and  post  cava  on  its  way  to  the  diaphragm. 

{d).  The  depressor  in  the  rabbit  is  formed  by  the  union  of  a  branch  from  the 
vagus  and  superior  laryngeal,  extending  mesial  to  the  sternal  artery  and  dorso- 
mesial  to  the  carotid,  (See  Stirling,  p.  302).  The  depressor  is  the  smallest  of  the 
three  nerves. 

[e).  The  femoral  artery  lies  between  the  femoral  vein  and  the  anterior  crural 
nerve.  The  vessels  are  just  under  the  skin,  ventral  side  of  the  proximal  part  of  the 
thigh,  parallel  with  the  femur.     (Stewart  p.  177). 

.(/■).  The  sciatic  nerve  lies  on  the  dorsal  side  of  the  prbximal  part  of  the  thigh. 
Make  an  incision  on  the  external  surface,  median  line,  and  separate  the  skin  with 
hooks.  Part  the  muscles  with  the  handle  of  the  scalpel.  The  sciatic  lies  deep 
between  the  muscles.     The  vastus  externus  may  be  cut  if  thought  best, 

B.     Blood  Pressure  Tracing. 

In  connection  with  this  experiment,  if  two  animals  are  used,  one  may  be  used 
for  determination  of  the  circulation  time  or  for  transfusion  with  warm  saline  solu- 
tion. Put  a  dog  under  Morphia  (10c,  c.  2  per  cent  sol.).  Setup  an  induction  ma- 
chine arranged  for  an  interrupted  current.     Fill  both  arms  of  the  manometer   with 


I 


Outlines  of   Experimental  Physiology  49 

mercury  to  the  height  of  about  10  cm  Attach  a  rubber  tube  to  the  proximal  arm  of 
the  manometer  and  fill  with  a  25  per  cent  solution  of  Mag-nesium  sulphate  or,  better, 
a  saturated  solution  of  Na2C03.  Be  sure  that  all  the  air  is  out  of  the  tube  and  this 
end  of  the  manometer.  Blow  into  the  rubber  tube  so  as  to  cause  a  difference  in  the 
two  limbs  of  about  10  cm  of  mercurj'.  Without  releasing  the  pressure,  clamp  the 
tube.  Attach  the  tube  and  clamp  to  the  free  curved  end  of  the  Guthrie  manometer, 
a  T  to  the  other  end,  connected  with  a  bottle  of  salt  solution.  Arrange  the  writing 
point  of  the  manometer  float  so  that  it  will  write  on  a  smoked  drum.  Keep  the 
needle  in  contact  with  the  drum  without  undue  friction  Below  the  pressure 
tracing,  tace  a  time  tracing,  having  the  marker  beating  seconds.  Fasten  the 
animal  on-the  holder,  back  down.  Give  either.  Insert  the  tracheal  canula  (for  the 
purpose  of  artificial  respiration).  Avoid  cutting  the  blood  vessels.  Insert  a  glass 
canula,  three  wa3',  one  armed  with  a  rubber  tube,  into  the  central  end  of  the  carotid. 
Leaving  the  forceps  on  the  artery,  fill  the  canula  and  tube  with  Mg-SO^  or  Xao 
CO 3  saturated  solution.  Now  connect  with  the  manometer,  being  very  careful  that 
all  connections  are  well  filled  with  the  solution  of  MgS04.  Before  taking  off 
the  bulldog  forceps  be  sure  to  get  the  line  of  zero  pressure.  Take  off  the  forceps 
and  allow  the  drum  to  revolve  at  slow  speed.  The  writing  point  of  the  manometer 
will  trace  a  curve  ,'get  record  of  height  and  pressure),  showing  an  elevation  for  each 
heart-beat  and  longer  waves  due  to  the  movements  of  respiration.  Which  part  is 
due  to  inspiration?     Is  the  pressure  higher  in  inspiration  or  expiration? 

Order  of  work. 

1.  Notes  on  the  anaesthetic. 

2.  Zero  pressure  in  Hg.  and  abscissa  line  on  the  drum. 

3.  Blood  pressure   curve. 

(a)  Expose  the  crural  or  sciatic  in  one  leg.  Double  ligature  and  divide. 
Stimulate  the  central  end;  the  blood  pressure  piobablj'  rises  and  the  heart  may  be 
accelerated.  Stimulate  the  peripheral  end  of  the  nerve.  There  is  little  change  in 
the  blood  pressure  and  none  in  the  heart. 

(b)  Now  expose  and  ligate  the  vago-sympathetic  nerve  in  the  neck.  Ligature 
double  and  cut  between  the  ligatures.  Stimulate  first  the  peripheral,  then  the 
central  end  and  note  the  effect  on  the  blood-pressure  curve.  Signal  during  stimu- 
lation. 

(c)  Expose  and  divide  the  other  vago-sj-mpathetic  while  a  tracing  is  being 
taken.     Again  stimulate  the  central  end,      Effect? 

(d)  Again  stimulate  the  peripheral  end  of  the  vagus  of  both  at  the  same  time, 
while  a  tracing  is  being  taken  and  see  how  long  it  is  possible  to  keep  the  heart 
from  beating.     (May  cause  death  of  dog). 

(c)  Effect  of  Intravenous  Injection  of  Nicotine  of  'i  c.  c.  of  0  1  per   cent   solution 
Inject  carefully  to  prevent  the  entrance  of   air  into   the   femoral    vein,    clamped 

with  bull-dog  forceps  in  a  dog.     What  is  the  effect  on  the  heart,  blood  pressure    and 

respiration' 

D.   Effect  of  transfusion  on  the  blood  pressure. 

(a)  While  a  tracing  is  being  taken,  inject  slowlj-  about  100  c.  c.  normal  saline 
solution  heated  to  40°  C)  ,  through  a  canula  in  the  femoral  vein,  by  means  of  a 
funnel  supported  by  a  stand  at  such  a  height  that  the  solution  runs  in  easily.  A 
stop  cock  inserted  between  the  funnel  and  canula  should  be  closed  bef«re   the  funnel 


50  Outlines  of  Experimental  Physiology 


is  empty,  so  as  to  ob%iate risk  of  getting  air  into  the  vein.  Continue  to  inject  por- 
tions of  100  c.  c.  until  a  distinct  change  in  pressure  has  occurred.  Keep  a  record 
of  the  amount  injected  and  when  the  first  change  in  pressure  was  seen,  and  mark 
the  time  of  each  injection  on  the  curve.  After  3o  minutes,  again  measure  the  height 
of  mercurj^  in  the  manometer.      (Kef.  Brodie  p.  177-18U.) 

E.  Effect  of  Haemorrhage  on   blood  pressure. 

Note  the  scale  of  the  manometer.  While  a  tracing  is  being  taken,  draw  off 
10  c.  c.  of  blood  from  the  femoral  artery  and  notice  whether  any  effect  is  produced 
on  the  tracing.  Mark  the  tracing  the  moment  the  removal  of  blood  begins  and 
ends. 

Now  run  off  10  c.  c.  of  blood  and  note  the  eft'ect  on  the  blood  pressure.  If  none 
occurs  run  off  10  c.  c.  at  a  time  until  the  pressure  falls,  noting  the  amount  of  blood 
removed  and  the  change  in  pressure. 

F.  Circulation  Time. 

Methylene  blue.  A  0.2  per  cent  methylene  blue  in  0.6  per  cent  XaCl  solution  is 
warmed  to  40  °  C.  and  placed  in  a  burette,  sloped  to  make  an  angle  with  the  hori- 
zontal, 5  in.  above  the  level  of  the  canula.  Expose  the  external  jugular  and  place 
two  ligatures  under  it — compress  the  cardiac  end  with  bull-dog  forceps  and  tie  the 
head  end.  Insert  a  three  way  canula  and  tie  it  in  place  with  the  second  ligature. 
Fill  the  canula  and  rubber  tube  with  a  saline  solution  by  means  of  a  long  pointed 
pipette.  Be  sure  to  exclude  the  air.  Expose  the  carotid  of  the  opposite  side. 
Place  under  it  a  piece  of  sheet  rubber  and  between  the  rubber  and  the  artery  a 
piece  of  white  glazed  paper.  Connect  the  canula  (free  from  air)  with  the  burette. 
Concentrate  the  light  on  the  carotid;  gee  the  time  record  .started;  and  the  moment 
the  methj-iene  blue  flows  into  the  jugular,  close  the  key  to  the  signal  (Write  above 
the  time).  Allow  10  c.c.  or  more  to  flow  in,  and  again  signal  when  the  blue  ap- 
pears in  the  carotid.  Take  as  many  observations  as  possible  and  calculate  the 
mean  circulation  time  of  both  the  greater  and  lesser  circulations. 

G.  To  Expose  the  Heart. 

(a).  After  the  introduction  of  the  respiratory  canula,  make  a  median  incision 
over  the  sternum  from  the  anterior  to  the  posterior  tip.  Strip  the  skin  back  to  the 
junction  of  the  costal  cartilages  and  ribs.  Place  strips  of  absorbent  cotton  wet 
with  a  half  saturated  solution  of  tannic  acid  along  the  cut  surfaces.  With  strong 
scissors,  cut  quickly  through  the  costal  cartilages  of  both  sides,  parallel  with  the 
sternum,  clamping  the  mammary  arteries. 

Study  the  relation  of  the  heart  to  the  pericardium  and  other  structures  in  the 
thorax.  Note  changes  in  the  form,  color,  and  tension  as  felt  by  the  hand  during 
the  cardiac  cycle.  As  long  as  artificial  respiration  is  continued,  it  will  hardly  be 
possible  to  kill  the  dog. 

(b).  If  asphyxia  curves  are  desired,  close  the  trachea,  tie  the  animal  firmly  in 
place  and  obtain  the  characteristic  Traube-Herring  curves. 

(c).  If  asphyxia  curves  are  not  desired,  open  the  right  auricle.  The  animal 
will  then  quickly  bleed  to  death  without  pain  or  convulsions. 

{d).     Autopsy — Note  the  lungs,  kidney  and  bladder. 


Outlines  of  Experimental  Physiology  51 

H.     Electrical  Methud. 

A  canula  connected  with  a  burette  containing  a  1.5  per  cent  NaCl  solution  is 
tied  into  a  jugular  vein.  For  the  lesser  circulation  time,  a  carotid  is  then  isolated 
and  laid  on  bent  insulated  platinum  electrodes.  To  further  secure  insulation,  a 
piece  of  india-rubber  is  slipped  between  the  artery  and  the  tissues.  The  artery, 
by  means  of  electrodes,  is  connected  as  one  of  the  resistances  in  a  wheatstone  bridge 
(induction  coil  for  interrupted  current — one  cell  in  the  primary  and  a  telephone 
instead  of  a  galvanometer  according  to  Kohlrausch's  method  of  measuring  resistances 
of  electrolj-tes).  The  bridge  is  balanced  by  adjusting  the  resistance  until  the  sound 
heard  in  the  telephone  is  at  its  minimum  intensity-.  One  c.c.  of  saline  solution  is 
run  into  the  jugular.  Reaching  the  artery  it  causes  a  diminution  of  electrical  resis- 
tance. This  disturbs  the  balance  of  the  bridge  and  the  sound  in  the  telephone 
becomes  louder.  The  time  from  the  beginning  of  the  injection  to  the  alteration  in 
the  sound  is  the  circulation  time  between  the  jugular  and  carotid,  read  off  b}"  the 
time-marker  on  the  drum  with  a  signal,  gives  the  circulation  time. 

Expt.  LIV.  A.  Effect  of  Suprarenal  on  Respiration,  Heart  Action  and  Blood 
Pressure. 

Have  all  apparatus,  drugs,  graduated  tubes  and  vessels,  electrodes,  etc.,  read 3'. 
Do  not  cut  the  drum  paper  for  the  pressure  curve.  Put  the  time  record  on  each 
drum.  Set  off  at  a  slow  rate  and  have  electro-magnetic  signal  in  each  circuit  to 
record  the  stimulations  and  time  of  giving  drugs.  Use  shielded  electrodes  and  a 
weak  current.  For  1  per  cent  adrenal  extract,  take  2  gr.  capsule  to  12  c.c.  of  0.7 
per  cent  XaCl,  1  gt.  acetic  acid.  Boil,  filter,  and  make  up  to  12  c.c.  Make  up  also, 
a  2  per  cent  adrenalin  solution.  Fasten  the  dog  with  a  chain  and  inject  6-10  c.c. 
of  2  per  cent  morphine.  Have  sawdust  ready.  Again  note  the  changes  produced 
by  morphine.  Fasten  the  dog  to  the  board,  giving  a  little  ether,  if  necessary  Xote 
changes  in  the  eye,  re  r,iiration  and  heart. 

OPERATION. 

For  blood  and  respiratory  pressure. 

(a)  Clip  the  hair  from  the  neck  and  jaw  of  one  side.  Make  a  2-3  inch  median 
incision,  beginning  below  the  larynx.  Expose  both  carotids.  Tie  the  head  end, 
put  the  bull-dog  forceps  on  the  heart  end,  and  ligature  in  the  three  way  canula  for 
connection  with  the  manometer,  through  tubing  filled  with  a  saturated  solution  of 
Nag  CO 3.     Expose  both  vagi  and  place  silk  finders   under  them. 

Next  connect  the  trachea  through  tubes  on  one  side  with  the  respiratory  bottle 
and  the  other  with  the  ether  bottle,  if  necessary,  or  not  until  after  normal  curves  are 
secured.  Put  a  finder  under  the  superior  laryngeal.  Expose  the  femoral  vein,  con- 
nect the  canula  and  keep  the  bull-dog  forceps  on  the  vein  or  rubber  tubing  above  the 
canula  to  exclude  the  air  except  just  when  injecting  and  then  be  sure  to  expel  the 
air  from  the  canula  with  a  long  pipette  or  syringe.  Clamp  off  the  vein  before  all 
the  fluid  from  the  pipette  enters.     Place  a  silk  finder  under  the  crural  nerve. 

ORDER  OF  WORK. 

Get  normal  curves  of  respiration,  blood  pressure  and  heart  action.  (Connect 
the  respiratorj'  bottle  with  the  tambour  and  T  from  the  trachea.     Be  sure  all  is  air- 


52  Outlines  of  Experimental  Physiology 


tight  and  connections  close  tog-ether).  An  abscissa  line  is  obtained  for  both  on  a 
slowly  moving  drum.  Have  the  time  record  and  electric  signal  ready  for  use.  Re- 
move the  bull-dog  and  get  the  blood  pressure  and  a  short  curve  on  the  one  drum  and 
at  the  same  time  obtain  a  normal  respiratory  curve  on  another  slovirly  moving  drum, 
using  electrical  signal  and  time  marker.  Stop  the  drums.  The  dog  in  the  meantime, 
is  breathing  fresh  air. 

C.  Stimulate.  Cut  the  crural  nerve  while  the  dog  is  breathing  from  the  bottle. 
Note  the  signal  and  get  curves.  Stimulate  the  peripheral  end  of  the  crural  nerve. 
Effect? 

D.  Inject  about  4  c.  c.  adrenalin,  1  per  cent  (be  careful  not  to  inject  air)  and 
clamp  off.  Start  all  the  drums  a  few  seconds  before  injecting  into  the  femoral  vein 
and  at  the  moment  of  injecting,  mark  on  all  the  drums  with  electric  signal,  the  time 
of  injection.  Obtain  curves.  Obtain  curves  showing  the  influence  of  drugs  on 
blood  pressure,  respiration  and  heart;  then  stimulate  the  crural  nerve  again  and 
note  the  effect. 

E.  Effect  of  stimulating  the  vagus.  Ligate  twice,  cut  between  the  ligatures 
stimulate  the  central  end  then  the  peripheral  end  of  the  other  vagus,  then  stimulate 
again  the  superior  laryngeal.     Note  the  time  and  get  the  curves  on  all  the  drums. 

H.     Inject  3  c.  c.  2  per  cent  adrenalin  and  get  curves. 

I.  Get  asphyxia  tracing  showing  Traube-Herring  curves.  Be  sure  to  tie  the 
animal  firmly;  or,  if  the  animal  is  in  good  condition  and  time  permits,  obtain  first 
the  circulation  time  and  the  effect  of  transfusion  or  hemorrhage  as  described  in  the 
experiment  on  blood  pressure;  then  obtain  asphyxia  tracings  by  clamping  the 
trachea. 

B.  Effect  of  Suprarenal  Extract  on  Secretion,  Respiration,  Blood  pressure 
and  Heart  Action.  Have  all  apparatus,  drugs,  graduated  tubes  and  vessels,  elec- 
trodes, etc. ,  ready.  Put  the  time  record  on  each  drum,  set  off  at  a  slow  rate  and 
have  an  electro-magnetic  signal  in  each  circuit  to  record  the  stimulation  and  the 
time  of  injecting  drugs.  Use  shielded  electrodes  and  a  weak  current.  For  1  per  cent 
adrenalin  extract,  2  gr.  capsule  to  12  c.  c.  of  0.7  per  cent  NaCl  plus  Igt.  Acetic 
acid,  boil  filter  and  make  up  to  12  c.  c.  Prepare  also  0.2  per  cent  adrenalin 
solution.     Note  the  rate  of  respiration,  the  temperature,  and  the  pupil. 

(2).  Fasten  the  dog  with  a  chain  aud  inject  6-10  c.  c.  of  2  per  cent  Morphine- 
Have  sawdust  ready.  Again  note  the  change  produced  by  morphine.  Fasten  the 
dog  to  the  board,  giving  a  little  ether,  if  necessary.  Note  the  changes  in  the  eye, 
respiration  and  heart. 

OPERATION. 

As  for  blood  and  respiratory  pressure,  (a).  Clip  the  hair  from  the  neck  and 
jaw  of  one  side.  Make  a  2-6  inch  median  incision,  beginning  below  the  larnyx. 
Expose  the  carotid  on  the  side  opposite  to  the  one  selected  for  the  operation  on  glands 
or  for  the  transfusion  experiment:     also  both  carotids. 

Tie  the  head  down,  put  bull-dog  forceps  on  the  heart  end  and  ligature  in  the  canula 
for  connection  with  the  manometer  through  tubing  filled  with  a  saturated  solution 
of  NagCos.  After  having  exposed  the  vagus  on  both  sides,  placing  black  silk  find- 
ers under  them  and    ligatures   under  the  superior   laryngeal,    connect  the  trachea 


Outlines  of  Experimental  Physiology  53 

through  the  tube,  on  one  side  with  the  respiratory  bottle  and  on  the  other  side  with  the 
ether  bottle  and  bellows,  if  necessary,  but  not  until  the  normal  curves  are  secured. 

{fi).  Expose  the  femoral  vein,  insert  the  canula  and  keep  the  bull-dog-  forceps 
on  the  vein  or  rubber  tubing  above  the  canula,  to  exclude  the  air,  except  just  when 
injecting  from  the  burette  or  S3'ringe;  and  then  be  sure  to  expel  the  air  from  the 
canula  with  a  long  pipette.  Clamp  off  the  vein  before  all  the  fluid  from  the  pipette 
enters  it. 

(3).  Effect  on  Secretion.  Note. —Study  carefully  the  submaxillary  region  on 
the  dead  animal 

{a).  The  anterior  limit  of  the  median  cut  made  to  expose  the  trachea,  ma}' be 
carried  through  the  skin  to  the  angle  of  the  jaw,  avoiding  the  external  jugular  and 
noting  the  following  directions,  or  the  following  plan  may  be  used. 

(6).  Make  an  incision  parallel  and  along  the  inferior  median  border  of  the  lower 
jaw  about  1cm.  distant  from  the  border,  only  through  the  skin.  The  cut  will  be 
carried  from  about  the  middle  to  near  the  angle  of  the  lower  jaw.  Carefully  divide 
the  platysma  myoides  and  expose  the  external  jugular  with  its  branches.  Ligate 
doubly  such  branches  as  are  in  the  way  and  cut  them,  except  those  that  carrj-  blood 
from  the  glands.  It  may  be  only  the  branches  extending  anteriorly  above  the  jaw 
border  that  need  be  ligated.  Feel  for  the  facial  artery  at  the  border  of  the  jaw  and 
masseter,  between  the  digastric  and  masseter.  Ligate  it  Loosen  the  digastric 
from  the  jaw  border  to  its  insertion.  There  ligate  twice  and  cut  between  the  liga- 
tures. Lift  the  digastric  and  notice  just  beneath,  the  broad  .mj'lohj'oid  with  its 
nerve  lying  on  it.  Carefully  lift  the  mj'lohj-oid  and  the  lingual  nerve  and  the  ducts 
will  then  come  to  view.  The  mylohyoid  may  be  cut  parallel  to  and  near  the  jaw- 
border,  avoiding  the  facial  artery  and  ducts.  Ligate  the  branch '  of  the  facial  that 
supplies  the  digastric.  The  lingual  nerve  is  then  seen  emerging  from  under  the 
border  of  the  jaw,  about  }<  the  distance  from  the  angle  of  the  jaw  to  the  angle  of  the 
mouth,  a  little  nearer  the  masseter  or  jaw  angle,  and  extends  anteriorly  and  trans- 
versely toward  the  median  line,  across  both  ducts,  then  forward  to  the  tongue  par- 
allel to  the  larger  hypoglossal.  Ligate  and  cut  the  lingual  nerve  far  from  the 
border  of  the  jaw,  lift  the  lingual  nerve  b}-  the  ligature  and  trace  it  back  to  the  jaw- 
where  its  chorda  t3-mpani  branch  is  seen  running  back  along  the  duct.  Ligate  the 
lingual  central  to  the  chorda,  so  that  the  chorda  can  be  placed  on  electrodes.  Insert 
an  angular  canula  into  the  larger  duct  (the  one  nearer  the  ramus  of  the  jaw),  after 
placing  a  small  bull-dog  forcep  on  the  duct.  To  reach  the  sympathetic,  divide  the 
hypoglossal  nerve  just  where  it  crosses  the  carotid  and  raise  the  central  end.  Close 
to  the  inside  of  the  carotid  lies  the  vagus  and  when  it  is  raised,  the  sympathetic  is 
seen  underneath.  The  sympathetic  from  this  point  goes  separately  to  the  superior 
cervical  ganglion — from  this  ganglion,  fibres  accompany  the  carotid  to  the  gland. 
The  sjmpathetic  fibres  may  be  ligatured  and  later  cut  for  stimulation  with  a  weak 
induction  current,  or  the  sj-mpathetic  branch  may  be  traced  bj'  means  of  the  cervical 
vagus  to  the  cervical  ganglion. 

ORDER  OF  WORK. 

A.     Note.     Get  normal  curves  of  respiration  (one  end  of  T  from  the  trachea  goes 
to  the  respiratory  bottle,  the  other  to  ether),  blood  pressure  and  heart-action. 


54  Outlines  of  Experimental  Physiology 

(1).  Abscissa  line  for  zero  pressure  is  obtained  on  both  slow  moving-  drums. 
Have  the  time  record  and  electric  sig-nal  ready  for  use.  Remove  bull-dog-  and  get 
the  blood  pressure  and  a  short  curve. 

(2).  at  the  same  time  obtain  a  normal  respiratory  curve  on  the  other  slow- 
moving  drums,  using  the  electric  signal  and  time  marker.  Stop  the  drums,  the  dog 
in  the  meantime  breathing  fresh  air. 

(3).  Have  a  5.  c.  c.  graduate  placed  at  the  mouth  of  the  canula  inserted  in 
Wharton's  duct,  shielded  electrodes  on  the  chorda  and  on  the  sympathetic.  Stim- 
ulate for  an  exact  leugth  of  time  about  (3  sec.)  with  definite  strength,  weak  induc- 
tion current.  Note  every  IS  sec.  the  height  of  the  secretion.  Then  stimulate  the 
sympathetic  exactly  as  the  chorda  was  in  time  and  strength.  Note  the  number  of 
drops   secreted  every  IS  sec, 

(4).  Note  the  pupils  and  temperature. 

C.  Action  of  Atropin. 

Inject  into  the  femoral  2.  c.  c  of  0.1  per  cent  atropin.  Just  before  injection,  ob- 
tain curves  of  the  blood  pressure,  respiration,  and  heart  and  note  with  the  signal, 
the  time  of  injection.  Obtain  curves,  showing  the  influence  of  the  drug  and  stimu- 
late the  chorda  and  then  the  sympathetic  as  before — same  time  and  strength  of 
current — and  note  for  each  IS  sec,  the  amount  of  secretion  in   drops. 

D.  Effect  of  Section  of  Vagi. 

Ligate  twice  and  cut  between  the  ligatures  on  one  vagus.  Connect  the  head 
end  of  one  with  the  shielded  electrode.  Just  before  ligating  and  cutting,  obtain 
a  short  distance  curve  for  pressure,  respiration  and  heart.  Stop  the  drum  until 
ready  to  cut,  then  cut  and  note  the  time  of  cutting  with  the  signal. 

E.  Effect  of  Stimulation  of  one  Vagus. 

Stimulate  the  head  end  of  the  vagus  for  a  few  seconds  noting  the  time  with 
signal  and  obtain  curves  of  pressure,  respiration,  and  heart.  Repeat,  stimulating 
the  heart  end.  Ligate  and  cut  the  other  vagus.  Simulate  first,  the  head  and  then 
the  heart  end  of  the  vagus, 

F.  Effect  of  4  c.  c.  of  2  per  cent  Adrenal  Extract. 

Just  before  injecting  4  c  c  adrenal  extract  of  2  per  cent.  Obtain  a  curve. 
Note  the  time  of  injection  and  the  effect  on  pressure,  respiration,  heart  and 
secretion,  stimulation  as   before. 

G.  Effect  of  3  c  c.  Adrenal  Extract. 

Just  before  injecting  3  c.  c.  of  2  per  cent  adrenal  extract,  get  short  length  of 
curves  and  note  the  time  of  injection  and  the  effect  on  blood  pressure,  respiration 
heart  and    secretion. 

H.     Get  asphyxia  tracing  showing  Traube-Herring  curves. 

Expt.  LV.  The  Nervous  Regulation  of  the  Respiratory  Movements.  (See 
Stewart,  p.  188.) 

Set  up  the  apparatus  after  the  following  directions  and  see  tliat  it  is  air-tight. 
A  recording  tambour  is  connected  to  a  large  bottle  through  a  double  perforated  cork. 
One  hole  is  used  for  regulating  the  pressure  by  means  of  a  clamp.  From  a  hole  in 
the  lower  edge  of  the  bottle,  make  connections  with  a  T  tube  to  an  ether  bottle  and 


Outlines  of  Experimental  Physiology  55 

from  there  to  a  canula  and  thence  to  the  trachea.     Have    also   an   inductorium     and 
electrodes  arranged  for  an  interrupted  current,  and  a  signal. 

Anaesthetize  a  cat.  Insert  a  canula  into  the  trachea  and  connect  with  the 
bottle.     Set  off  the  drum  at  a  slow  speed  and  take  a  tracing-. 

(2).  Clamp  off  the  ether  bottle  and  remove  the  clamp  from  the  large  bottle  for 
air.  Dissect  out  the  vagi  in  the  lower  part  of  the  neck,  pass  the  ligature  under 
them  but  do  not  tie.  Close  the  tube  in  the  large  bottle  and  while  a  tracing  is  being 
taken,  tie  the  crural.  Then  stimulate  its  central  end  with  weak  shocks,  marking 
the  time  of  stimulation  on  the  drum.  Repeat  the  stimulation  with  strong  shocks' and 
take  a  tracing.     Stimulate  the  peripheral  end;  note  the  effect. 

(3).     Cut  the  vagus;  stimulate  the  central,  then  the  peripheral  end. 

(4).  Apply  a  strong  solution  of  potassium  chloride  with  a  camel's  hair  brush  to 
the  central  end  of  the  vagus,  while  a  tracing  is  being  taken,  and  observe  the  effect 
— slowing- or  expiratory  stand  still. 

(5).  Open  the  regulating  tube.  Isolate  the  superior  laryngeal  branch  of  the 
vagus,  which  will  be  found  coursing  inwards  to  the  larynx  at  the  level  of  the  thy- 
roid cartilage.  Ligature  the  nerve  and  divide  it  between  the  larj-nx  and  the  liga- 
ture. Close  the  tube  and  take  a  tracing;  then  cut  it.  Stimulate  first  with  weak 
then  with  strong  currents,  the  central  end  of  the  superior  laryngeal.     Effect  ? 

(6).  Open  the  reg-ulating  tube  while  a  tracing  is  being  taken;  cut  and  stimulate 
the  central  and  heart  end  of  the  other  vagus.     Effect  ? 

(7).  Isolate  both  carotid  arteries  for  as  great  a  distance  as  possible.  Take  two 
pieces  of  lead  tubing  about  nine  inches  long  and  bend  up  about  two  inches  at  each 
end,  nearly  to  a  right  angle.  Place  one  end  of  each  of  the  tubes  in  contact  length- 
wise with  each  carotid,  securing  contact  with  loose  ligatures.  Support  the  tube 
in  clamps,  so  that  the  arteries  are  not  pressed  upon.  Connect  two  adjacent  ends  of 
the  tubes  b}' a  short  rubber  tube.  Connect  one  of  the  remaining  ends  to  a  funnel, 
supported  on  a  stand,  and  the  other  to  a  rubber  tube  hanging  over  the  edge  of  the 
table  above  a  jar,  Slip  two  or  three  folds  of  paper  between  the  tube  and  the  vagus 
nerve.  Heat  two  or  three  litres  cff  water  to  60  oC.  Now  take  a  tracing  while  the  hot 
water  is  passing  through  the  tube  to  the  jar.  Mark  on  the  tracing  the  point  at 
which  the  circulation  of  the  hot  water  was  begun,  and  go  on  passing  it  until  an  ef- 
fect was  produced.  Then  stop  the  drum  and  circulate  water  at  ordinary-  tempera- 
ture till  the  breeithing  is  again  normal.  Then,  while  a  tracing  is  being  taken,  pass 
ice  cold  water  through  the  tubes — note  the  effect. 

(8t.  Effect  of  hemorrhage.  Insert  a  canula  into  the  carotid  artery.  While  a 
tracing  is  being  taken,  allow  the  blood  to  flow.  Dyspnoea  and  exaggeration  of  the 
respiratory  movements  will  be  seen  when  a  considerable  quantity  of  blood  has  been 
lost.  Mark  and  varnish  the  tracings.  Tie  the  animal  T  tubes  firmly  or  they  will 
be  pulled  out.  Note  the  first  effect  and  the  amount  of  blood  lost  when  the  effect  set 
in. 

In  the  whole  of  this  experiment  the  clamp  on  the  regulating  tube  is  to  be  open 
except  when  the  lever  is  actually  writing  on  the  drum,  in  order  that  the  period  dur- 
ing which  the  animal  must  breath  into  the  confined  space  of  the  bottle  may  be  di- 
minished as  much  as  possible.  The  clamp  on  the  tube  from  the  ether  bottle  is  to  be 
closed  except  when  more  ether  is  needed. 

Expt.  LVI.     Determination  of  the  Lung  Capacity,  by  Means  of  the  Spirometer. 
Always  clean  the  mouth  piece  with  corrosive  sublimate  before  using. 


56  Outlines  of  Experimental  Physiology 

(1.)  Tidal  Air.  Partially  fill  the  reservoir  of  the  spirometer  with  air  and 
then  breathe  normallj'  several  times  throug-h  the  mouth-piece  and  have  the  helper 
record  the  upper  and  lower  limits  of  each  respiration.  The  average  of  these  esti- 
mates should  give  the  normal  tidal  air.     Do  not  watch  the  scale. 

(2).  Complimental  Air — Have  the  spirometer  nearl}'  full  of  air.  Take  a  few  normal 
breaths  through  the  mouth  piece,  having  the  assistant  make  a  record  of  the  reading  of 
the  instrument  at  the  close  of  each  expiration.  Then  take  as  deep  an  inspiration 
as  possible  and  note  the  reading  of  the  instrument. 

(1).  Supplemental  Air.  Have  a  small  amount  of  air  in  the  reservoir  of  the 
spirometer.  Breathe  regularly  a  few  times,  making  records  of  the  upper  and  lower 
limits.   Then  exhale  as  strongly  as  possible  and  then  make  note  of  the  scale  reading. 

(4).  Vital  Capacity.  Have  the  spirometer  set  at  zero.  Inhale  as  deeply  as 
possible  and  then  exhale  through  the  mouth  piece  all  the  air  you  can.  This  will 
be  the  greatest  possible  amount  of  air  which  can  be  forced  out  of  the  lungs  when 
filled  to  their  greatest  extent. 

(5).  Determine  the  average  rate  of  respiration  at  different  times  during  the  day, 
during  exercise,  fatigue,  and  rest. 

Expt.   LVII.     Respirator^'  Pressure. 

Fasten  the  tube  of  a  pneumometer  with  a  little  cotton  wool  in  one  nostril;  breathe 
through  the  other  with  closed  mouth  and  observe  the  amount  by  which  the  mercury  is 
altered  in  ordinary  inspiration  and  expiration. 

(b).  Repeat  the  observation  with  forced  breathing  once  a  second,  also  evei-y  two 
seconds,  pinching  the  tube  at  the  height  of  inspiration  and  expiration.  Read  off 
the  maximum  inspiratory  and  exspiratory  pressure. 

(c).     Repeat  (o)  with  the  tube  covered  with   rubber;  held  between  the   teeth  and 

with  the  nostrils  open. 

(d).     Repeat  {b)  with  the  tube  in  the  mouth  and  the  nostrils  closed. 

Expt.  LVIII.     Chest  measurements  with  calipers. 

(a).     Dorso-ventral  at  the  heighth  of  the  sixth  rib  (junction  with  sternum). 

(b).     Doro-ventral  at  the  height  of  the  ninth  rib 

(c).     Lateral  at  the  height  of  the  sixth  rib. 

{d).     Lateral  at  the  height  of  the  ninth  rib. 
Obtain  both  phases  of  quiet  and  forced  breathing. 

Compare  carefully  these  measurements  with  those  obtained  in  the  following 
related  experiments   LIX   and   LX   and  fill  out  the  anthropometric  record. 

Expt.  LIX.  The  Stethograph  records  the  movements  of  the  chest  wall,  the 
curves  indicating  the  relative  time  between  inspiration  and  expiration  and  with  the 
curves  obtained  with  a  thoracometer,  show  the  difference  in  diameter  or  width  at 
difi'erent  levels  of  the  thorax  in  inspiration  and  expiration,  and  these  should  agree 
with  the  caliper  and  tape  measurements.  In  making  observations  with  the  stetho- 
graph, the  subject  should  sit  with  his  back  or  side  to  the  table.  The  observer  may 
readily  adjust  the  stethograph  to  record  any  lateral  dorso-ventral  diameter  of  the 
thorax. 

For  all  observations  upon  the  respiratory  changes  in  the  body,  the  subject 
should  keep  the  parts  of  the  body  symmetrically  disposed. 


Outlines  of  Experimental  Physiology  57 


Observations. 

(1.)  How  much  may  be  learned  of  man's  respiratory  movements  bj'  simple 
inspection?     Make  a  careful  enumeration  and  record. 

(2.)  Adjust  the  stethograph  and  make  a  record  of  the  lateral  diameter  of  the 
thorax  at  the  ninth  rib.  Does  the  stethograph  show  more  than  can  be  learned  from 
inspection?  If  so,  what?  Note  the  diflerence  between  inspiratory  and  expiratory 
curve  and  time. 

(3.)  Take  a  stethogram  of  the  lateral  diameter  at  the  ninth  rib.  How  does 
it  differ  from  2    ?     Account  for  the  difference. 

(4.)  Take  a  stethograph  of  the  dorso-ventral  and  lateral  diameter  of  the  thorax 
over  the  lower  end  of  the  gladiolus.  Compare  with  the  records  of  forced  inspiration 
and  expiration  at  this  region. 

(5.)  Take  a  lateral  ninth  rib  stethograph- while  the  subject  reads  a  paragraph; 
sighs;  coughs;  and  laughs.     Account  for  the  peculiarities. 

(6  )  Take  a  lateral  ninth  rib  stethograph  after  the  subject  has  taken  vigorous 
exercise.     What  changes  are  to  be  noticed? 

(7.)  After  a  series  of  stethographs  have  been  taken  for  others,  compare. 
Determine  the  essential  features;  give  cause  of  these. 

(8.)  Seek  the  causes  of  the  differences  which  exist  between  stethographs  of 
different  individuals.  May  they  be  accounted  for  bj'  stature,  condition,  occupation 
or  habit 

Expt.  LX.  The  Thoracometer  curves  bear  an  accurate  ratio  to  the  movements 
of  the  chest. 

Remove  from  the  stethograph  the  wooden  rod  which  bears  the  receiving  tambour 
and  slip  thereon  the  lever,  computing  its  magnification  for  use  in  determining  the 
variations  in  thoracic  diameters.  So  adjust  the  lever  that  the  slightest  movement  of 
the  button  will  be  instantly  responded  to  by  the  lever. 

(1.)  Carefully  measure  the  arms  of  the  lever  to  determine  how  much  the  tracing 
point  of  the  lever  will  move  for  every  millimetre  that  the  button  moves. 

(2.)  When  the  button  is  pressed  outward  in  inspiration,  in  what  direction 
does  the  lever  move? 

Take  tracings  of  the  changes  in  the  dorso-ventral  diameter  at  the  level  of  the 
nipples.  Determine  by  measuring  the  tracing  how  much  the  dorso-ventral  expan- 
sion is.     What  is  the  average  expansion  during  forced  respiration? 

Make  a  similar  series  of  observations  on  the  lateral  diameter  in  the  plane  of  the 
nipples. 

(5.)^  Repeat  observations  on  the  lateral  and  dorso-ventral  diameter  at  the 
ninth  rib. 

ANTHROPOMETRIC  DATA  (Thoracic). 


Name   Home Flat  or  Hills 

Age   ....   Height .Weight Previous  Occupation 

Habit.  Inactive,  Active.  .Tennis,  Bicjxling,   etc, ; 

Condition, .  .Fat,  Lean,  Medium,  Muscular,  Flabby Lung  Capacity. 

Respiratory  Pressure  from  Pne'umonometer 

Ordinary  Inspiration Ordinar}'  Expiration  

Forced  Inspiration  Forced  Expiration . 


58  Outlines  of  Experimental  Physiology 

Girth  of  Chest  in  Nipple  Plane, 

(1.)     In  Repose   Ord    Inspiration   Ord.  Expiration Expansion.. 

Girth  of  Chest  at  Xinth  Rib. 

(1  )      In  Repose Forced  Ins Forced  Exp Expansion. .. 

Diameter  of  Chest  at  Xipple  Plane. 

Dorso-Vcntral. 

(1.)     In    Repose Ord.    Insp Ord.  Exp Expansion 

(2. )     Forced  Ins Forced  Expir Expan 

Lateral. 

(1.)     In  Repose   Ord.  Insp Ord.  Exp Expansion 

(2. )     Forced  Insp Forced  Exp Expansion 

Diameter  of  Chest  at  Plane  of  Ninth  Rib. 

Dorso-vcntral. 

(1),     In  Repose Ord.  Ins Ord.  Exp Expan 

(2).     Forced  Ins Forced  Exp Expan 

Lateral. 

(1).     In  Repose     ....... .Ord.  Ins Ord-  Exp Expan 

(2).     Forced  Ins   Forced  Exp Expan   

Date Examiner 

Exp.  LXI.     The  Stethog-oniometer. 

The  purpose  of  this  instrument  is  to  record  the  outline  of  any  horizontal  section 
of  the  thorax,  though  it  could  be  used  as  well  for  tracing-  the  periphery  of  the  abdo- 
men, of  the  head,  or  of  a  limb.  To  use  the  stethogoniometer  for  the  purpose  here 
intended,  let  the  subject  sit  beside  a  table  upon  a  stool  adjustable  for  height.  So 
adjust  the  stool  as  to  bring  the  circumference  of  the  thorax  to  be  observed,  even  with 
the  upper  surface  of  the  table.  Fix  the  point  c  of  the  instrument  to  the  table,  Let 
the  observer  locate,  with  pen  or  pencil,  upon  the  side  of  the  subject  distal  from  the 
table,  a  point  which  shall  serve  as  a  starting  point. 

When  the  point  b  of  the  instrument  rests  upon  this  point  of  the  subject". s  thorax, 
the  instrument  should  be  well  extended  and  in  equilibrium  Fix  a  sheet  of  paper  to 
the  table  under  the  recording  pencil  at  a.  To  take  a  graphic  record  of  the  contour 
of  the  thorax,  proceed  as  follows: 

(a).  Let  the  observer  place  the  tracing  point  b  upon  the  .starting  point  in  the 
distal  side  of  the  thoracic  perimeter.  Let  the  subject  also  sit  with  hi.s  back  to  the 
table  and  take  his  record. 

(b).  Sweep  the  tracing  point  quickl}^  around  one-half  the  perimeter  to  a  point 
approximately  opposite  to  the  starting  point. 

(c).     Rotate  the  curved  arm  of  the  instrument  upon  its  axis  through  180  ^  . 

{d).  Sweep  the  tracing  point  around  the  other  half  of  the  perimeter  to  the 
starting  point. 

(e).  The  movements  of  the  tracing  point,  b,  in  the  horizontal  plane  have  been 
faithfully  recorded  upon   the   sheet  of   paper   by   the   recording   pencil    at  a.     It  is 


Outlines  of  Experimental  Physiology  59 

hardlj'  necessar}'  to  remind  the  student  that  the  subject  must  remain  motionless 
duriny  the  observation. 

Take  a  thoracic  j^erimeter  with  the  chest  in  repose.  Measure  different  diamet- 
ers of  the  tracing-  and  multiply  by  5  to  reduce  to  actual  measurements. 

Take  a  tracing-  at  the  end  of  forced  expiration;  at  the  end  of  forced  inspiration. 
Compare  diameters. 

Make  a  series  of  these  tracings  for  different  individuals.  Compare.  Formulate 
conclusions. 

Expt    LXII.     Cardio  Pneumatogram. 

Breathe  quietly  or  suspend  respirjition  for  a  short  period  during-  which  a  trac- 
ing of  the  pulse  transmitted  through  the  air  of  the  respir^itory  passag-es  through  the 
tube  in  the  mouth  or  nose  to  the  tambour  which  records  the  movements  on  the  drum. 
Let  some  member  count  the  pulse  of  the  experimenter  at  the  same  time  and  compare 
wi^h  your  record. 

Expt.  LrXIII.  Determination  of  Carbon  Dioxide  and  Oxygen  in  Inspired  and 
Expired  Air. 

in).  Estimation  of  Carbon  Dioxide,  Fill  a  burette  with  water  and  close  the 
pinch  cock  on  the  rubber  tube.  Immerse  the  wide  end  of  the  burette  in  a  large  ves- 
sel of  water  and  fill  it  with  carbon  dioxide  by  putting-  into  it  the  tube  from  the  car- 
bon dioxide  reservoir  to  the  graduated  point.  Hold  the  burette  in  a  vertical  position, 
its  mouth  being-  still  immersed,  make  the  level  of  the  water  the  same  inside  and  out 
and  read  off"  the  meniscus.  Then  introduce  a  piece  of  stick  sodium  hydrate,  close 
the  burette  with  the  finger  or  a  cork,  lift  it  out  of  the  water  and  by  a  sort  of 
see-saw  movement,  shake  the  sodium  hydrate  repeatedlj^  from  end  to  end.  Again 
immerse  the  burette  and  read  oft"  the  menisus.  Most  of  the  gas  will  be  absorbed. 
Repeat  the  shaking.     If  the  reading  is  just  the  same,  the  absorption  is  complete. 

{d).  Estimation  of  Inspired  Air.  Fill  the  burette  with  the  air  of  the  laboratory. 
Open  the  pinch  cock  and  immerse  the  wide  end  of  the  burette  till  the  water  reaches 
the  graduation.  Then  close  the  cock  and  read  off  the  meniscus.  Introduce  a  piece 
of  sodium  hj'drate  and  jiroceed  as  in  (a).  Notice  that  there  is  no  appreciable  absorp- 
tion. This  method  is  not  suitable  for  the  small  Jimount  of  carbon  dioxide  present 
in  ordinary  air.  Now  introduce  under  the  water,  some  pyrogallic  acid.  This  can 
be  done  conveniently  by  wrapping  some  of  the  crystals  in  thin  paper,  so  as  to  form  a 
kind  of  cigarette  which  is  pushed  up  into  the  burette.  A  little  more  sodium  hydrate 
may  be  added  if  the  first  introduced  is  entirely  absorbed.  Shake  as  described  in 
(«),  until  no  more  absorption  is  noticed.  Then  read  oft"  the  meniscus  again,  always 
making  the  level  the  same  inside  and  outside  of  the  burette.  The  difterence  in  the 
two  readings  gives  the  amount  of  oxj'gen  present.  "What  remains  in  the  burette  is 
nitrogen  (and  a  little  argon).  Its  amounl  is,  of  course,  equal  to  the  reading  of  the 
burette  plus  the  capacity  of  the  ungraduated  part  in  the  narrow  end  of  the  burette, 
which  must  be  determined  by  a  separate  measurement 

{c).     Analj'sis  of  Expired  Air. 

Fill  the  spirometer  with  water,  breathe  into  it  several  times  in  your  ordinary 
way,  but  be  careful  not  to  inspire  any  air  from  the  spirometer;  then  fill  the  burette 
with  the  air  from  the  spirometer.  Or  simply  expire  several  times  through  the  bur- 
ette, seeing  that  none  of  the  inspired  comes  from  it.  Determine  as  in  Ux)  and  (f>), 
the  percentage  amount  of  carbon  dioxide,  oxygen  and  nitrogen. 


60  Outlines  of  Experimental  Physiology 

{d).  Repeat  (c)  with  air  expired  after  the  lungs  have  been  thoroug-hly  ventilated 
by  taking  a  number  of  deep  breaths  in  succession  and  determine  whether  there  is 
anj-  difference  in  the  percentage  amounts. 

For  calculating  gasses  where  the  gas  is  not  each  time  as  it  should  be  placed, 
so  that  water  inside  and  outside  is  on  a  level.     If  not  on  a  level,  use  the  following 
calculation. 
VP  =  vp. 

V     =  volume  of  gas  under  atmospheric  pressure. 
P     =  atmospheric  pressure  under  water  =  950  cm.  (76  X  12.5). 
v      =  volume  of  gas  under  lowered  pressure. 
p      =  atmospheric  pressure  minus  the  height  of  water  in  the  tube. 

Expt.  LXIV.     Mechanics  of  Respiration. 

Artificial  Scheme.     Follow  the  directions  attached  to  it. 

Expt.  LXV.     Chemistry  of  Respiration. 

Estimation  of  oxygen  carbon  dioxide  and  water. 
Apparatus.  Two  aspirator  bottles  with  a  box;  wooden  tray  containing  a  jar  for  a 
guinea  pig  and  six  bottles; — Nos.  1  and  4  filled  with  soda  lime  to  absorb  CO 2  :  Nos. 
2,  3,  and  5  filled  with  pumice  stone  soaked  in  H2SO4  to  absorb  moisture:  No.  6,  a 
MuUer  valve  to  prevent  the  air  being  forced  back  through  the  series  of  bottles  by  a 
wrong  coupling  of  the  aspirator  tubes. 

(a).  Weigh  bottles  3,  4,  and  5  (4  and  5  together).  Place  the  guinea  pig  in  the 
jar  and  weigh.  During  one  hour  draw  air  through  bottles  1  to  6  by  placing  an  as. 
pirator  bottle  on  its  box  and  allow-ing  the  water  to  flow  from  this  bottle  to  the  one 
remaining  on  the  desk.  The  rubber  connecting  tube  must  be  changed  when  the  as- 
pirator bottles  are  changed.  After  one  hour,  w^eigh  bottle  3  and  bottle  4  and  5. 
Tabulate  the  results  as  follows. 

Weight  of  jar  and  guinea  pig  at  the  beginning grams. 

Weight  of  jar  and  guindea  pig  at  the  end    grams. 


Loss   grams. 

Weight   of  bottle  2  (H2SO4)  at  the  beginning, grams. 

Weight  of  bottle  2  (H2SO4)  at  the  end, grams. 


Gain  (water  absorbed)    

Weight  of  bottles  4  and  5  at  the  beginning,    grams. 

Weight  of  bottles  4  and  5  at  the  end, grams. 


Gain  (CO^  absorbed) 

Total  water  and  CO 2  absorbed 

Loss  in  weight  of  jar  and  guinea  pig 

Difference  (oxygen  absorbed) 

Respiratory  quotient 

Expt.  LXVI.      Electro-Physiological  Apparatus.     Battery  or  cell. 
I.     Single  fluid  cells,     (a).     Place  small  Zn  and  Cu  plates  in  separate  vessels 
of  10  per  cent  sulphuric  acid.     Note  the  action. 


Outlines  of  Experimental  Physiology  61 

$ 

(b).  Place  Zn  and  Cu  plates  in  the  same  vessel  (unconnected  by  wire)  of  10  per 
cent  sulphuric  acid.  Note  the  action  when  near  and  far  apart  and  write  the  chemi- 
cal reactions. 

(c).  Connect  the  plates  by  wire  for  an  instant.  Note  the  action — reaction.  Di- 
rection of  current?     Place  each  wire  separately,  then  together  on  the  tong^ue;  result? 

(d).  Amalgamate  the  zink  plate  (see  footnote).  Pure  zink  in  H2SO4  gives  off 
a  few  bubbles  verv  slowU'. 

Now  repeat  {c)  and  note  the  differences  between  (<:)  and  (d).  Place  the  plates  far 
apart  and  then  close  together  while  the  wires  are  on  the  tongue.  Note  the  differ- 
ences. Illustrate  and  label  all  the  parts  of  a  single  fluid  cell.  Name  the  ions  set 
free.  If  H  is  electro-positive,  a  poor  conductor,  offering  great  resistance  to  the  flow 
of  the  current — what  effect  may  it  have  upon  the  direction  of  the  current? 

(e).  Place  the  electrodes  on  a  piece  of  filter  paper  containing  a  little  starch  and 
Kl.  Close  the  circuit.  A  dark  blue  spot  indicates  the  anode  or  X  pole.  (Iodine  is 
set  free  at  the  anode). 

(/").     From  experiment  (e)  which  plate  has  the  positive  pole?     Give  the   reaction. 

II.  Double  Fluid  Cells,  (a).  Daniell  cell, — illustrate,  naming  the  parts  and 
solutions,  reactions,  anions,  and  kations,  determine  with  KI  and  starch  which  is 
the  positive  pole. 

(b).  What  advantage  does  it  posses  over  the  single  fluid  cell  in  regard  to 
polarization  and  constancy  of  currents?     Use  of  porous  cup. 

(c).  Which  pole  gives  acid  and  which  alkaline  reaction,  as  proved  with  litmus 
paper? 

III.  Leclanche  or  Dry  Cell.  Illustrate  and  name  the  parts  as  seen  in  the 
separated  cell.  Write  the  reaction.  Why  ought  they  not  be  used  for  long  periods 
of  time?  And  what  effect  has  rest?  Test  the  poles  with  KI  and  starch,  with 
litmus. 

Foot  Note.  {a).  Chemically  pure  zinc  does  not  need  amalgamation,  commercial 
zinc  contains  iron,  arsenic,  etc,,  as  impurities,  the  contact  of  unamalgamated  zinc  and 
these  dissimilar  metals  with  an  electrolj'te,  causes  a  difference  of  potential  and  paras- 
itic currents  run  from  the  zinc  to  the  foreign  metals.  These  currents  are  prevented  by 
covering  the  impurities  with  zinc  amalgam,  the  electro-motive  properties  of  which 
toward  sulphuric  acid  are  those  of  pure  zinc.  As  the  zinc  in  the  amalgam  dissolves 
out,  the  mercurj'  unites  with  fresh  zinc.  Zinc  is  best  amalgamated  by  cleaning 
with  10  per  cent  sulphuric  acid  and  then  rubbing  on  mercury  with  a  brush. 

(b).  If  the  current  passes  through  a  solution,  decomposition  takes  place,  elec- 
trol3'sis,  the  ions  are  set  free  and  may  adhere  to  the  plates,  setting  up  currents  in 
the  opposite  direction  and  weaken  the  original  current.  The  poles  are  touched  to  a 
solution  of  KI  and  starch.  Decomposition  is  effected,  in  that  Iodine  is  separated 
and  goes  to  the  plus  pole,  unites  with  starch  to  form  a  blue  spot. 

(c).  The  zinc  is  arbitrarily  taken  as  the  positive  plate,  the  copper  as  the  nega- 
tive. The  pole  attached  to  the  negative  plate  is  the  positive  pole  or  anode;  that  at- 
tached to  the  positive  plate,  is  the  negative  pole  or  cathode. 

(d).  The  latent  chemico-phj'sical  energy  of  the  cell  is  transformed  into  electri- 
cal energy  which  becomes  manifest  in  the  contact  spark,  movement  of  the  galvanic 
needle  or  lifting  of  the  armature  of  a  magnet.  If  the  copper  plate  of  a  cell  were 
weighed  before  and  after  using  the  cell,  it  would  be  found  that  it   had    increased    in 


62  Outlines  of   Experimental  Physiology 

« 

weig-ht.  The  amount  of  electrolysis  is  an  index  of  the  amount  of  current  afPorded 
by  a  cell;  e.  g-.,  if  the  negative  pole  were  attached  to  a  cup  containing-  Ag-NOs  and 
the  positive  pole  to  pure  silver  immersed  in  the  AgNOs,  it  would  be  found  that  one 
ampere  of  current  will  uniformly  deposit  0.001118  grams  silver  upon  the  cup  in  one 
second.  This  is  known  as  the  unit  of  current  or  ampere.  A  dry  cell  with  little  ex- 
ternal resistance  can  produce  a  current  of  about  %  ampere.  The  unit  of  resistance 
is  the  ohm.  It  is  the  resistance  offered  to  a  current  by  a  column  of  mercury  1  sq. 
mm.  cross  section  and  106.8  cm.  long,  or  of  pure  silver  wire  1  mm.  by  1  metre.  The 
electromotive  force  is  measured  in  volts.  The  relation  of  the  units  of  measurements- 
are  expressed  in  Ohm's  formula, — C=E/R. 

For  our  work,  the  cells  are  arranged  in  series;  that  is,  the  zinc  of  one  is  attach- 
ed to  the  copper  of  the  other. 

Expt.  LXVII.     Keys  or  Switches. 

A.  Simple  Contact  Key.  Illustrate,  showing-  the  direction  of  the  current  by 
arrows. 

B.  Du  Bois  Reymond  Key.  [a].  As  a  simple  contact  key.  {b).  As  a  short 
circuiting  key;  i.  e.,  so  that  the  current  goes  back  to  the  cell.  Prove  with  starch 
and  KI,  using  two  cells. 

C.  The  Commutator,      (a).     Set  up  for  a  simple  key. 

(b).  As  a  double  key;  e.  g.,  for  two  n.  m.  p.  so  as  to  send  the  current  "to  either 
of  two  pairs  of  wires. 

{c).  Set  up  so  as  to  change  the  direction  of  a  current.  Illustrate  diagrammat 
ically,  showing  the  direction  of  the  current  with  arrows. 

Expt.  LXVIII.     The  Galvanometer. 

In  order  to  study  the  difference  of  potential,  or  direction  and  strength  of  a  cur- 
rent, a  galvanometer  or  electrometer  is  employed .  In  the  galvanometer,  the  points 
of  different  potential  are  connected  by  a  coil  of  wire  near  which  is  suspended  a  mag- 
net. When  the  circuit  is  completed,  the  electrical  energy  acts  on  the  suspended 
magnet  by  induction  and  deflects  it  to  an  extent  proportionate  to  the  current.  A 
mirror  is  attached  to  the  magnet  by  means  of  which  a  beam  of  light  is  reflected  to- 
ward the  scale.  The  mirror  and  magnet  are  suspended  by  very  delicate  fibres; 
hence,  when  not  in  use,  must  always  be  protected  by  a  support  which  is  moved  in 
place  by  the  lower  screw. 

Adjust  the  eye  piece  so  that  the  cross  hair  is  in  the  focal  plane  and  the  scale 
reading  distinctly  seen.   . 

[a).  Connect  the  terminal  posts  through  a  simple  key  and  a  resistance  of  about 
2000  ohms,  to  the  poles  of  a  small  battery  made  of  Cu  and  Zn  strips  dipping  into 
dilute  H3SO4.  Note  the  direction  and  extent  of  the  deflection  of  the  mirror  on  the 
scale. 

(b).     Reverse  the  poles  of  the  battery.     Result? 

{c).     Increase  the  resistance.     Result. 

Expt.  LXIX.  The  Voltmeter.  Connect  a  dry  cell  through  a  simple  key,  so 
that  the  positive  pole  (the  one  joined  to  the  carbon  plate)  is  connected  with  the  plus 
binding  post.  Close  the  key  and  note  the  voltage  of  the  cell  as  indicated  by  the 
pointer.  Repeat  this  with  another  cell,  then  join  the  two  cells  in  series  and 
ascertain  the  combined  voltage.     Does  it  agree  with  the  sum  of  the  two? 


Outlines  of  Experimental  Physiology  63 


Expt  r^XX  The  Milainmeter  indicates  the  streng^th  of  the  current  or  amperes 
directlj'.  The  scale  of  the  one  employed  in  this  laboratory  is  calibrated  in  one  half 
thousands  of  an  ampere.  You  determined  the  voltage  of  the  dry  cell;  and  to  ascer- 
tain its  amperage,  connect  the  positive  pole  of  the  cell  through  a  simple  key  to  the 
positive  binding  post  of  the  milammeter  and  read  off  the  current  from  the  scale;  add 
two  or  more  cells  and  note  the  scale  reading. 

Be  sure  never  to  connect  more  than  twelve  cells  in  the  circuit  with  the  milammeter 
and  never  join  the  negative  pole  of  the  cell  with  the  positive  binding  post  of  the  mil- 
ammeter. 

Expt  LXXI.  The  resistance  of  the  cell  (internal  resistance)  and  the  external 
resistance  in  the  circuit  are  determined  by  means  of  the  Wheatstone  Bridge. 

Expt.  LXXII.  Differences  of  Electrical  Potential,  especially  very  small  dif- 
ferences, are  also  determined  b^'  means  of  the  capillary  electrometer.  The  direc- 
tions for  its  use  and  an  explanation  of  it,  are  posted  with  the  apparatus. 

Expt.  LXXIII.     Graduating  the  Strength  of  the  Current. 

From  the  formula  C  =  E/R,  it  is  evident  that  the  current  ma3'  be  altered,  eith- 
er by  var5'ing  the  E    M.  F  ,  or  by  altering  the  resistance. 

If  two  poles  of  a  cell  or  other  points  of  difference  of  potential  be  joined  by  a  well- 
drawn  wire,  the  potential  through  the  wire  will  uniformly  fall  from  the  anode  to  the 
cathode.  The  greater  the  resistance  in  the  wire,  the  more  uniform  will  be  the  fall  in 
potential.  By  means  of  the  rheostat  we  are  able  to  send  more  or  less  of  the  current  of  a 
voltaic  cell  through  a  nerve  or  muscle  by  changing  the  resistance  of  the  current.  This 
is  done  by  putting  a  long  thin  wire  into  the  circuit,  the  current  being  inversely  pro- 
portional to  the  resistance.  The  greater  the  resistance,  therefore,  the  smaller  the 
current.  Since  the  strength  of  the  galvanic  current  depends  upon  the  character 
and  number  of  the  cells  employed  and  the  total  resistance  in  the  circuit,  the  strength 
of  the  current  can  be  easily  varied  b3^  altering  the  resistance,  since  C  =  E/R. 
There  are  a  number  of  forms  for  this  purpose.  One  convenient  form  is  the  rheostat 
which  is  a  box  containing  coils  of  known  resistances,  connected  with  brass  plates. 
The  current  enters  bj'  the  binding  posts,  passes  from  block  to  block  through  thick 
plugs  of  verj^  low  resistance.  If  the  plugs  are  pulled  out,  the  current  travels  coils 
of  wire  of  known  resistances.  Another  method  of  altering  the  strength  of  current  is 
to  employ  some  form  of  shunt  to  split  the  current  so  that  only  part  passes  the  nervei 
i.  e  ,  an  arrangement  b}'  which  a  greater  or  less  proportion  of  current  can  be  sent 
through  the  galvanometer;  e.  g  ,  if  the  plugs'  resistances  are  labeled  and  the  resis- 
tance of  the  galvanometer  known,  then  1-9  plug  inserted  indicating  the  ratio  be- 
tween the  resistance  of  the  galvanometer  and  itself  and  1-10  of  the  current  is  sent 
through  the  galvanometer.  A  current  takes  the 
path  of  least  resistance  and  if  two  paths  are 
open  to  it,  more  or  less  can  be  sent  through  one 
of  them  by  decreasing  or  increasing  the  resis- 
tance in  the  other. 

The  simple  rheostat  of  10  meters  or  more  fine  wires  stretched  on  a  board  and 
combined  with  slider  and  binding  posts  so  that  more  or  less  of  the  wire  can  be  put 
into  the  circuit  bj'  changing  the  slider  or  attachments  of  the  posts  is  the  modified 
form  of  the  one  used  in  the  labor atorj*. 


64  Outlines  of  Experimental  Physiology 

Divided  circuits.  If  a  circuit  divides  into  two  branches  at  A,  uniting  tog-ether 
again  at  B,  the  current  w^ill  also  be  divided.  The  relative  strength  of  current  in 
the  tvpo  branches  will  be  proportional  to  their  conductivities,  i.  e.,  inversely  propor- 
tional to  their  resistances.  If.  r  be  a  wire  of  2  ohms  and  r'  of  3  ohms,  current  r  will 
be  to  current  r'  as  3  :  2;  or  3-5  of  the  current  will  flow  through  r  and  2-5  through  r'. 
The  joint  resistance  of  the  two  currents  will  be  less  than  that  of  one  branch  because 
the  current  now  has  the-choice  of  both  and  the  conductivity  will  be  the  sum  of  the 
two  and  the  joint  resistance  will  be  R. 

It    follows    that  yR   =   /r    +  /r'  =      ^  ^^'^'     or     ^^^        >^  + /s 

rr' 

and  R= —  = -S-    which  is  less  than  2.      or 

r+r'         ® 

the  joint  resistance  of  the  divided  conductors  will  be  the    product    of  both 
resistances  divided  by  their  sum. 


(1).     Rheostat  in  Series. 

Connect  a  cell  through  a  simple  key  with  a  galvanometer  or  milammeter  and 
introduce  the  rheostat.  Connect  the  positive  pole  of  the  cell  to  the  plus  or  zero  post 
of  the  rheostat  and  from  the  post  marked  3  to  the  other  post  of  the  galvanometer,  in- 
troduce a  wire.  Tabulate  results.  If  necessary,  shunt  the  galvanometer  by  con- 
necting its  binding  posts  through  about  4ohms  resistance  wire.  Then  introduce 
the  rheostat  in  the  galvanic  circuit  with  gradually  increasing  resistances.  Re- 
sult and  Conclusions? 

(II).     Rheostat  in  Parallel. 

Divide  the  current.  When  the  resistance  in  the  galvanometer  is  very  high, 
then  the  fraction  of  the  potential  of  the  cell,  passing  through  the  galvanometer  will 
be  directly  proportional  to  the  fraction  of  the  resistance  in  the  rheostat.  Divide 
the  current  so  that  X)  /^)  Hf  and  1  respectively,  of  the  current  passes  through  the 
galvanometer.  Connect  each  pole  of  the  battery  through  a  key  with  the  end  poles  of 
the  rheostat  and  from  the  o  pole  and  the  other  pole  of  the  simple  rheostat,  chosen 
as  the  one  that  gives  the  desired  fraction  of  the  whole  resistance  of  the  i-heostat,  con- 
nect wires  to  the  galvanometer.  This  will  give  practically  the  fraction  of  the  cur- 
rent desired. 

Tabulate  results  and  prove  your  conclusions  by  determining  the  voltage  with 
the  voltmeter  and  record  your  readings  for  comparison. 

A  milammeter  may  be  used  instead  of  a  galvanometer,  since  the  resistance  is 
only  210  ohms,  the  readings  are  not  perfectly  correct. 

From  the  arrangement  of  our  apparatus,  you  notice  that  from  the  cell  through 
the  rheostat  back  to  the  cell  makes  a  complete  circuit.  Having  reached  the  metal- 
lic slider  (S),  the  circuit  has  two  paths  presented.  .. 


Outlines  of  Experimental  Physiology  65 

First,  from  S  to  B.  vSccond,  from  S  throuf,'^h  G  back  to  B.  The  total  current  is 
divided  into  two  parts;  C  which  passes  along-  the  wire  from  S  to  B  and  C,  the  derived 
circuit  which  passes  through  the  galvanometer.  Suppose  the  resistance  to  the  last 
named  current  is  R'  and  that  to  the  direct  current  is  R,  the  relative  strength  of 
these  two  currents  is  expressed  in  the  following  proportion; 

C':C::R:R'.  But  the  resistance  of  the  german  silver  wire  may  be  conveniently 
divided  into  100  equal  (100  r).  If  the  slider  be  placed  at  any  position  along  the  wire, 
say  at  X  centimeters  from  the  end,  then  the   formula    would    be   C':C::xr:R'.     C  = 

—  C  Suppose  that  R=l  ohm  (r=0.01  ohms);  R'=2  ohms  and  x=0,  i.  e.,  the  slider 
R'  * 

xr 
tobeatB.    Then  C'=:^  C  =0.     This  shows  that  no  current  will    then  pass  through 

the  galvanometer. 

(1),  What  is  the  relative  strength  of  the  two  currents  when  x=10?  Whem  x= 
50? 

(2).     What  is  the  relation  of  C  '  to  C  when  x  =  99?     When  x  =  100? 

From  this  course  of  reasoning,  it  is  evident  that  with  the  simple  rheostat  we  can 
vary  a  derived  current  from  zero  to  a  maximum  Just  what  the  value  of  the  derived 
currents  will  be,  will  depend  upon  the  voltage  of  the  cell  and  the  total  resistance 
and  its  distribution. 

Expt.  LXXIV.     Induction  Currents. 

A  most  useful  method  of  electrical  stimulation  of  living  tissues  is  by  the  induced 
current,  and  a  clear  idea  of  the  phenomenon  of  induction  must  be  obtained. 

(1).     Iron  filings  and  a  magnet.     Note  the  lines  of  force. 

(2).  Faraday's  Experiment. — Remove  the  secondary  (larger)  coil  of  the  induct- 
orium  from  its  slideway  and  connect  its  terminal  with  the  capillaj-3'  electrometer  or 
galvanometer.  Raise  the  brass  bridge  between  the  binding  posts,  that  nearly  or 
practically  all  the  electricity  produced  in  this  coil  will  pass  over  the  bridge,  instead 
of  bj'  the  relativelj-  long  thin  wires  leading  to  the  electrometer,  galvanometer  or 
milammeter.     Tr3'  a  magnet  near  the  galvanometer  without  the  coil.     Effect. 

Bring  the  meniscus  into  the  field.  If  the  galvanometer  is  used,  put  the  coil  far 
from  the  galvanometer  so  that  the  magnet  shall  not  affect  the  magnetism  of  the  gal- 
vanometer. Thrust  the  north  pole  of  the  magnetized  rod  within  the  coil  at  a  definite 
speed.  The  needle  will  move,  indicating  that  an  electric  current  has  been 
induced  in  the  secondar}-  coil.  The  meniscus  will  return  to  its  former  position. 
Evidently  the  induced  current  is  of  momentary'  duration.  Withdraw  the  mag- 
net quiclilyt  The  meniscus  will  move  in  the  opposite  direction.  Insert  the  south 
pole.  The  induced  current  now  has  the  direction  opposite  to  that  of  the 
current  inlu^e.l  by  the  insertioa  of  the  north  pole.  Withdraw  the  magnet 
quickly.  The  induced  current  has  the  direction  opposite  to  that  of  the  current 
induced  by  the  withdrawal  of  the  north  pole. 

Thomson,  210-211,  Induced  Currents.     106-109,  Magnetic  Field. 

Expt.  LXXV.  Lines  of  Force.  The  space  about  a  magnet  in  which  the  mag- 
netic forc3s  act  is  called  the  "field"  of  the  magnet.  If  very  fine  iron  filings  are 
dusted  through  a  muslin  cloth  on'io  a  thin  card  perforated  near  the  centre  by  a 
copper  wire  or  other  conductor,  and  a  strong  current  is  passed  through  the  wire, 
the  filings  will  arrange  themselves  in  concentric  circles   around   the   wire,  particu- 


66  Outlines  of  Experimental  Physiology 

larly  if  the  card  be  gently  tapped.     The  position  of   these   lines   of   force   shows  the 
direction  of  themag-netic  force  and  their  number  is  an  index  of  its  intensity. 

Expt.  LXXVI.  To  produce  electric  induction,  the  lines  of  magnetic  force  must 
be  cut  in  the  circuit.  Hold  the  magnet  at  right  angles  to  the  axis  of  the  coil;  and, 
keeping  it  in  this  position,  rapidly  advance  it  towards  the  coil. 

The  galvanometer  or  electrometer  will  show  no  current,  because  the  number  of 
the  lines  of  magnetic  force  which  pass  through  the  field  of  the  conductor  has  not 
been  altered, 

LXXVII.     Electric-magnetic  Induction. 

An  electro-magnet  may  be  used  in  place  of  the  bar  magnet  to  produce  induction. 
Connect  a  dry  cell  through  a  simple  key  with  the  galvanometer.  Get  the 
direction  of  the  deflection  with  a  cell  to  note  its  direction  in  the  galvanometer.  Then 
connect  the  posts  1  and  2  of  the  primar3^  coil.  Open  the  key.  When  the  current 
passes  through  the  primary  coil,  the  core  of  iron  in  the  coil  will  be  magnetized  as  is 
shown  bj"  its  attracting  the  head  of  the  Wagner  hammer.  (2).  Connect  the  posts 
of  the  secondary  coil  to  the  galvanometer.  Approach  the  primary  to  the  secondary 
as  in  the  experiment  with  the  magnet.  Get  the  direction  of  the  deflection.  With- 
draw the  primarj-  coil.  The  galvanometer  shows  the  presence  of  induced  currents 
as  before.  These  currents  are  momentary.  The  first  induction  current  is  inverse; 
i.  e.,  it  runs  round  the  second  arj'^  coil  in  the  direction  opposite  to  that  taken  by  the 
battery  current  in  the  primary'  coil-  The  second  induced  current  is  in  the  same  di- 
rection as  the  primary  current.  Place  the  coils  at  right  angles  to  each  other.  Ap- 
proach one  toward  the  other.  No  current  will  be  induced.  When  does  the  induced 
current  have  the  same  direction  as  the  battery  current?     At  make  or  break? 

(3).  Make  and  Break  Induction.  Open  and  close  the  key  in  the  primary  cir- 
cuit; thus  making  and  breaking  the  primary  current.  Is  the  effect  the  same  as  if 
the  primary  were  suddenly  brought  up  to  a  secondary  coil  from  an  infinite  distance 
and  removed  again?  Is  the  make  induction  current  in  the  opposite,  the  break  in 
the  same  direction  as  the  primary'  current?  Turn  the  secondary  coil  on  its  pivot 
until  the  axis  is  at  right  angles  to  the  primar}'  coil.  Make  and  break  the  primary 
current.  No  induction  will  take  place,  provided  the  angle  between  the  coils  is 
precisely  at  Q'J '-' . 

Expt.  LXXVIII.  The  Inductorium.  Examine  the  construction  of  the  induc- 
tor ium.  The  primary  coil  consists  of  a  few  turns  of  thick  wire.  More  turns  would 
increase  resistance  and  self-induction  and  the  counter  induction  set  up  in  each  turn  of 
the  primary  wire  by  the  passage  of  the  primary  current  through  the  neighboring 
turns  without  increasing  the  induction  effect  in  the  secondary  coil.  The  iron  core 
adds  to  the  number  of  lines  of  magnetic  induction  which  pas?  through  the  coils.  It 
has  been  already  shown  that  the  lines  of  magnetic  induction  produced  by  the  pas- 
sage of  an  electric  current  through  a  wire  are  closed  circles.  If  the  centre  of  the 
coil  were  filled  with  air,  most  of  the  circles  would  remain  closed  about  their  own 
wire,  for  air  is  not  readily  permeable  to  magnetism.  But  when  the  iron  core 
is  placed  within  the  coil,  the  greater  part  of  the  magnetic  induction  follows  the  iron 
(because  it  is  more  permeable)  from  end  to  end  of  the  core,  returning  outside,  through 
the  air.  The  number  of  effective  lines  is  increased,  if  bundles  of  iron  wire 
are  used  instead  of  a  solid  core,  because  no  induced  current  is  then  possible  through 


Outlines  of  Experimental  Physiology  67 

the  mass  of  iron,  as  would  be  the  case  in  a  solid  core      Such   a   current    would  slow 
the  speed  of  mag-netization  and  demag-netization. 

Expt  LXXIX.  The  secondary  coil  is  made  of  many  turns  of  fine  wire,  be- 
cause the  object  of  the  inductorium  is  to  transform  the  low  E.  M.  F.  of  the  cell  into 
the  high  E.  M.  F.  of  the  induced  current.  In  the  induction  coil,  as  in  other  trans- 
formers, the  electro-motive  force  in  the  primary  circuit  is  to  those  produced  in  the 
secondary  circuit  approximately  as  the  number  of  turns  of  wire  in  the  primary  is  to 
the  number  in  the  secondary  circuit.  If  the  induced  current  is  to 
be  passed  through  conductors  of  low  resistiince,  the  high  internal  resistance  of  the 
secondary  coil,  due  to  its  great  length  of  wire  will  be  of  importance  Place  a  dry  cell 
with  a  simple  key  in  the  primary  circuit  of  the  inductorium  (posts  1  and  2).  Con- 
nect the  secondary  coil  with  the  galvanometer.  Note  the  excursion  of  the  needle 
with  a  break,  iilso  a  make  induction  current.  Replace  the  secondary  coil  with  one 
of  fewer  windings.  Let  the  distance  between  the  primary  and  secondary  coil  be 
the  same  as  before.  The  excursion  of  the  needle  with  a  break  induction  current 
will  be  increased,  or  at  least  not  proportionately  diminished.  If,  on  the  other  hand, 
the  induced  current  is  to  be  passed  through  nerve,  muscle,  or  skin,  the  resistance  of 
the  secondary  coil  will  practically  be  nothing  in  comparison  with  the  enormous 
resistance  of  animal  tissue. 

Expt.  LXXX.  Repeat  the  preceding  experiment,  introducing  .  into  the  secon- 
dary circuit  a  high  external  resistance;  i.  e.,  nerve.  The  secondar3'  coil  with  many 
turns  of  fine  wire  now  causes  a  greater  deflection  of  the  galvanometer  needle  than 
the  coils  with  fewer  turns.  Note: — the  more  turns  used,  the  more  induction  currents 
or  E.  M.  F.  available. 

Expt.  LXXXI.  Interrupter.  Instead  of  making  and  brejiking  the  primary 
circuit  by  hand  an  automatic  interrupter  is  provided.  The  primary  circuit  passes 
through  a  screw,  the  point  of  which  conveys  the  current  through  a  flat  spring  upon 
which  is  mounted  an  iron  disk,  opposite  and  near  to  the  core  of  wire  in  the  primary' 
coil.  When  the  current  enters  the  primary  coil,  the  core  is  magnetized  and  draws 
upon  the  iron  disk  The  spring  to  which  the  disk  is  attached,  is  thereby  drawn 
away  from  the  screw  point  through  which  the  current  is  passing.  Thus  the  current 
is  broken  and  ceases  to  flow  through  the  primary  coil,  the  core  is  no  longer  magnet- 
ized, and  releases  the  iron  disk;  the  spring  again  makes  contact  with  the  screw 
point,  the  current  is  re-established,  only  to  be  at  once  again  broken.  Thus  a  rapid 
series  of  make  and  break  induction  currents  is  secured. 

(d).  Draw  a  diagram  of  the  primary  circuit  indicating  the  connections  of  the 
inductorium. 

Expt.  LXXXII.  (a)  Test  the  effect  of  a  galvanic  current,  1  cell,  simple  key 
and  electrodes  place  latter  on  the  tongue,  at  make  and  break. 

(b).  Extra  currents  at  opening  and  closing  of  the  primary  current.  Remove 
the  secondary  coil  from  the  inductorium.  Connect  pasts  1  and  2  of  the  primary  coil 
with  a  dry  cell,  using  a  key.  Fasten  the  ends  of  the  electrode  wires  to  the  same 
posts.  Close  the  primary  circuit  Place  the  electrode  points  against  the  tongue. 
Open  the  key.  Is  a  shock  felt?  It  was  caused  by  a  self-induced  current  developed 
in  the  primary  coil.  Is  it  stronger  at  make  or  break?  Illustrate,  showing  the  di- 
rection of  the  current. 


68  Outlines  of  Experimental  Physiology 

Expt.  LXXXIII.     Galvani's  Experiment. 

Decapitate  a  frog-,  fasten  the  hook  of  the  copper  holder  'carefully  throug-h  the 
vertebral  column  and  twist  the  holder  quickly  so  that  one  of  the  frog's  legs  comes  in 
contact  for  an  instant  with  the  insulated  rod.  The  other  leg  in  the  meantime,  is 
held  off  with  a  glass  rod.  Are  the  contractions  confined  to  one  leg  or  both? 
Explain. 

Expt.  LXXXIV.  Lay  the  frog  on  the  glass  plate  covered  with  moistened  filter 
paper.  Study  the  sciatic  plexus,  uotiug  the  number  of  fibers  that  compose  it  and 
their  origin. 

(a).  Make  a  V-shaped  wire  composed  of  zinc  and  copper  Touch  the  sciatic 
with  one  end  of  the  wire  and  the  muscle  with  the  other,  first  one,  then  the  other, 
then  together. 

(b).     Are  there  indications  of  fatigue  of  the  muscles? 

(c).     Note  whether  the  current    varies  with  zinc  on  the  muscle  or    copper   on  the 

muscle. 

(d).     Sartorius — alternately  and  together,  wires  on  the  eight  nerve  and  sartorius. 

(<?).     Sartorius  and  ninth  nerve  and  sartorius  and  tenth  nerve. 

(f).  Influence  of  moist  filter  paper.  Touch  the  paper  with  the  V  under  the 
preparation  and  one  of  the  nerves.     Result?     Why? 

(o-).  Isolate  the  eighth  nerve  with  rubber.  Put  zinc  on  the  eighth  nerve  and 
copper  on  the  filter  paper.     Which  muscle  twitched?     Which  did  not? 

(i).     Isolate  the  tenth  nerve  and  repeat  the  above.     Results? 

(/).  Put  copper  and  zinc  close  together  and  place  on  the  nerve.  Spread  them 
far  apart  and  place  them  on  the  nerve.  Results?  Two  zinc  points  on  the  nerve, 
one  on  the  nerve  and  the  other  on  the  muscle.     Results?     Two  copper  points. 

(k).  Test  polished  and  unpolished  tips  of  metals.  What  is  the  influence  of 
impurities? 

(/) .     Conclusions  for  above. 

Special  Physiology  of  Nerves. 

Expt.  LXXXV.     Chemical,  Thermal,  and  Mechanical  Effects  on  N.  M.  P. 

■General  rules  for  preparing  the  physiological  preparation. 

Then.  m.  p.  must  be  so  prepared  that  it  retains  its  functions;  therefore,  all 
pressure,  pulling,  catting  and  handling  must  be  as  far  as  possible  avoided.  Pre- 
pare it  rapidly  and  in  definite  order.  The  tissue  dries  on  exposure  to  the  air,  there, 
fore  keep  them  moist  fnot  wet)  with  isotonic  NaCl  solution  (m  /8). 

1.  Chemical.  Expose  the  brachial  nerve.  Sever  it  at  the  spinal  column  and 
cut  off  the  arm  with  the  skin  on.  Lay  the  nerve  arm  preparation  on  a  glass  plate. 
Place  saturated  NaCl  solution  or  NaCl  crystals  on  the  tip  of  the  nerve  and  in  a  few 
minutes  note  the  effect.  After  the  contractions  of  the  muscles  have  appeared,  cut 
off  the  free  end  of  the  neiwe. 

(2).  Fasten  the  arm  to  a  muscle  lever  or  lay  it  on  a  glass  plate  and  expose  the 
nerve  so  that  it  will  dry  rapidly.     What  is  the  effect? 

(3).  Make  a  nerve  muscle  preparation;  protect  it  in  the  moist  chamber.  Use 
tube  brush  reservoirs  for  the  different  solutions,  being  careful  to  wash  out  the  solu- 
tion before  adding  another  supply.     Lay  the  nerve  across  the  brushes  which  are  wet 


Outlines  of  Experimental  Physiology  69 

with  the  following-  solutions  that  are  to  be  tested:— m/8  sodium  citrate,  m/8  calcium 
chloriile,  m/s  sodium  oxalate,  m^  potassium  chloride,  m/10  nitric  acid,  m/10 
sodium  hydrate,  m/  2  cane  sug-ar. 

(4).  Is  the  stimulating^  action  of  a  salt  due  to  its  valency  and  charge?  Stimu- 
late the  end  of  a.  nerve  with  («)  monovalent  anion,  m^i  Nal,  also  NaBr,  m/g.  (6). 
Divalent  anion  Na2S04m/25  solution  (c),  Trivalent  anion,  sodium  citrate,  m/50. 
Note  the  results  regarding-  the  streng-th  of  the  solutions,  contractions,  heig-ht  and 
duration  of  the  effect.  Tabulate  the  results,  stating-  which  of  the  solutions  stimu- 
late and  which  do  not,  which  act  through  their  negative,  which  through  their  posi- 
tive charges?     What  is  the  effect  of  the  sugar  solution?     It  is  a  non-electrolyte. 

(5).  Prevent  NH4OH  vapor  from  reaching  the  muscle  by  covering  it  with  moist 
filter  paper,  place  the  ammonia  in  a  small  glass  sooon  and  let  the  nerve  dip  into  it. 
Effect?     Apply  ammonia  to  the  muscle.     Effect?     ' 

(6).     Apply  a  hot  needle  to  the  tip  of  the  nerve.     Result? 

(7).     Pinch  the  tip  of  the  nerve.      Effect? 

Expt.  LXXXVI.  Osmotic  Effects  The  contractility,  heat  production,  and 
other  phenomena  of  the  life  of  the  muscle,  rest  at  base  on  chemiciil  processes.  Any- 
thing that  sutificiently  destroys  these  processes  ma3'  be  a  stimulus.  A  most  import- 
ant source  of  stimulation  is  the  alteration  of  the  chemical  composition  of  muscle 
through  osmosis. 

(a).  Effect  of  distilled  water  on  sartorius  muscle?  Describe  it,  what  causes 
it?  Muscle  contains  globulins,  carbohydrates  (as  glycogen),  nitrogenous  and  other 
extractives,  water  and  inorganic  salts.  Most  of  them  require  inorganic  salts  for 
their  complete  solution.  Osmosis  of  salts  into  distilled  water  first  stimulates  and 
then  destroys  contractility. 

(b).  Effect  of  Strong  Salts  on  Muscle.  Place  the  sartorius  on  an  inclined  glass 
slide  so  that  the  lower  fourth  is  covered  with  NaCl  crystals.     Effect?     Why? 

(c).     Effect  of  Ions  upon  Muscle  Twitching. 

In  watch  crystals,  place  the  following  solutions  and  into  each  an  irritable 
muscle  that  has  been  found  to  contract  when  electrically  stimulated.  Any  of  the 
leg  or  abdominal  muscles  will  answer.  Notice  the  time  in  which  the  twitchings 
begin  and  in  which  solution  they  are  most  pronounced.  Are  they  due  to  valency 
and  electric  charge  of  ions?  m/!s  sodium  bromide,  m/16  sodium  phosphate,  m/ 32 
aluminium  chloride,  m/^  sodium  sulphate,  m/s  potassium  chloride,  m^s  calcium 
chloride. 

(d).  If  electrolytes  stimulate,  what  is  the  effect  of  non-electrolytes?  Um/g 
NaBr  stimulates,  put  a  muscle  in  a  sugar  solution  of  the  same  osmotic  pressure, 
m4  sugar  solution.     Effect? 

{e).  To  the  solution  in  (c)  which  produced  the  strongest  twitchings,  add  m^ 
CaCls,  one  part  CaCls  to  .50  parts  of  the  solution.  Effect?  That  is  about  the  os- 
motic pressure  of  the  calcium  in  the  blood.  What  is  the  effect  of  calcium  on  our 
muscles? 

Expt.  LXXXVII.    Muscle   Reaction. 

(a).   Test  the  reaction  of  muscle  on  red  and  blue  litmus  placed    in  contact. 

(ft).   Heat  a  muscle  to  40  ^  C  in  normal  NaCl,  test  the  reaction. 

(c).  Plunge  a  muscle  into  a  solution  of  NaCl  at  100  °  C.     Test  the  reaction. 


70  Outlines  of  Experimental  Physiology 


(d))  Tetanize  a  muscle  for  some  time.  Test  the  reaction  before  and  after  tetan- 
izing-.     Couclusions. 

Comparison  of  Make  and  Break  as  Stimuli.     (See  Stewart,  592 

Expt.  LXXX  VII.  A.  Constant  Current.  Arrang-e  X.  M.  P.  in  the  moist 
chamber. 

(a).  Connect  a  dry  cell  with  a  key  to  rheostat  in  parallel.  Use  different  cur- 
rents 3/40,  20/40,  40/40.     Ascertain  if  make  or  break  is    a  strong'er    stimulus    on 

the  nerve  of  a  N.  M.  P. 

(b).   Rapidly  make  and  break,   result? 

(c).   Try  (a)  and  \bj  on  the  muscle  through  the  binding-  post  on  the  lever. 

(•■/).  Weaken  the  current  until  make  and  break  no  longer  stimulate  when  the 
current  is  applied  to  the  nerve  of  the  X.  M.  P.  Which  disappers  first? 

B.  Induction  Currents. 

(1).   Shocks. 

(a)  Without  altering  the  strength  of  the  current  used  in  (d),  connect  the  wires 
to  posts  1  and  2  of  the  inductorium  and  connect  the  wires  from  the  secondary  posts  of 
the  moist  chamber  leading  to  the  nerve  of  the  N.  M.  P.  Make  and  break  the  cur- 
rent.    Result? 

(&).   Then  when  the  secondary  is  at  an  angle  make  and  break.     Result? 

(6)  When  it  is  far  from  the  primary  make  and  break.      Result? 

[d)  Move  the  secondary  toward    the    primary    until    the    threshold    value    is 
found.     Does  the  muscle  contract  at  make  or  break? 

(e)  Cautiously  move  the  secondary  until  both  make  and  break  stimulate. 

{/).  Try  o^  muscle.  Note  the  distance  of  the  primary  from  the  secondary.  la 
a  stronger  current  needed?     How  much  stronger? 

(II)  Interrupted  Current. 

(a).  Posts  2  and  3,  close  the  short  circuiting  key,  appl}'  the  electrode  to  the 
nerve,  then  close  the  primary  key.     Effect? 

(b).   Open  the  short  circuiting  key,  result? 

Expt.  LXXXIX.  A.   Exclusion  of  make  or  break. 

(b)  Posts  1  and  2,  close  a  short  circuiting  ke3^  Place  the  electrodes  on  the 
tongue,  close  the  primary  key, — result?  Open  the  short  circuiting  key,  then 
open  the  primar3^     Which  was  excluded? 

(6)  Open  the  short  circuiting  key,  place  the  electrode  on  the  tongue  or  N.  M.  P. 
Close  the  primary  circuit.  Result?  Close  short  circuiting  ke3%  open  the  primary, 
— result?     Which  was  excluded,  make  or  break? 

B.  Modified  Method  of  Comparison  of  Make  and   Break. 

Induction  and  Constant  Currents.  Connect  a  cell  through  a  key  to  a  rheostat 
in  parallel.  Join  the  current  wires  to  posts  1  and  2  of  the  inductorium  and  from 
these  same  posts  to  a  simple  key  to  N.   M.    P. 

(a).  Close  the  primary  key  in  the  cell  circuit;  open  and  close  the  key  in  the  nerve 
circuit.     The  muscle  will  contract. 

(b).  Weaken  the  current  until  no  contraction  occurs  at  make  or  break  of  the 
nerve  circuit  key. 

{c).  Close  the  nerve  circuit  key  and  make  and  break  the  primary   key. 

{d).  When  do  you  get  induction  and  when  constant  current  stimulation?  Con- 
clusion? 


Outlines  6f  Experimental  Physiology  71 


Expt.  XC.  Muscle  Work. 

The  N.  M.  P.  in  the  moist  chamber  is  after  loaded;  i.  e.,  the  muscle  is  loaded 
only  during-  conlracticn,  the  vveig-ht  being^  supported  by  the  reg-ulating  screw. 
Place  the  nerve  across  the  N  P.  E.  Record  on  a  slow  movinff  drum,  with  the 
muscle  loaded  as  follows;  scale  pan  only  20,  40,  60errams.  Stimulate  with  the  same 
break  shocks,  placing-  the  sig-nal  in  the  primary  circuit.  Obtain  for  each  weight 
at  least  three  contractions  and  take  the  mean. 

(a).  State  the  influence  of  load  on  the  latent  period.  For  this  use  the  fastest 
rate  on  drum  and  time,  100  vibrations  per  second. 

(b),  Height  of  contractions  in  mm. 

(c).     Time  of  contraction  and  relaxation. 

{d).     Calculate  the  work  done  by  the  muscles. 

ie).     When  does  the  muscle  work  under  the  most  favorable  conditions? 

(/').  Determine  the  ratio  between  the  height  of  the  curve  traced  by  the  lever  and 
the  height  through  which  the  weight  was  raised. 

Let  W  =  the  work  done. 

g  =  the  height  of  the  curve. 

k  =the  constant  of  the  apparatus,  —in  this  place,  the  ratio  between  the  lever 
<irms. 

Then  W  ==  kgh. 

Expt.  XCI.     Summation  of  Stnnuli. 

Set  the  secondary  at  such  a  distance  from  the  primary  coil,  that  break  shall 
not  quite  cause  a  contraction.  Repeat  inadequate  single  stimulus  at  short  and 
regular  intervals.  After  a  time,  a  contraction  will  be  secured.  Inference?  Can 
you  cite  similar  results  in  practice? 

Expt.  XCII.     The  Effect  of  Previous  Stimulation. 

Set  off  the  drum  at  a  medium  rate.  Stimulate  N.  M  P.  with  break  shocks. 
Obtain  another  curve  but  as  the  lever  is  sinking  back  toward  the  abscissa,  stimu- 
late a  second  time.     Result? 

(A).  Draw  an  abscissa.  Use  an  indicator  for  the  stimulation  time.  Stimulate 
by  a  series  of  equal  strength  shocks  thrown  in  at  regular  intervals.  What  does  it 
indicate?     When  is  the  height  of  the  contraction  the  greatest? 

(c).     Summation  of  Stimuli-tetanus.     (Stirling,  219;  Stewart,  552-3;   Brodie,  59). 

Stimulate  with  maximum  make  and  break  shocks  causing  break  to  follow  be- 
fore the  relaxation  of  the  make  is  at  an  end.  Superimpose  5  or  6  contractions  caus- 
ing the  upstroke  of  each  successive  contraction  to  continue  the  upstroke  of  its 
predecessor. 

(d).     Use  the  wheel  interrupter  in  the  primary  circuit  with  the  key  closed. 

(e).  Send  the  interrupted  current  through  the  muscle  for  about  two  seconds. 
Inference? 

Expt.   XCIII.   Muscle  Fatigue. 

(a).  Arrange  the  automatic  contact  on  the  drum  to  break  the  primary  current. 
Use  the  induced  current  of  such  a  strength  that  break  shocks  onlj'  are  effective. 
P'asten  an}'  thick  muscle  in  the  clamp  and  weight  the  lever  with  30  grams  Stimu- 
late N.  M.  P.  Get  a  record  of  about  100  contractions.  Note  the  latent  period,  the 
phase   of  rising  and  sinking  energy.     Get  the  time  when  you   decide  on    the   fastest 


72  Outlines  of  Experimental  Physiology 

rate  of  motion.  Obtain  first  a  curve  on  the  same  abscissa  line  for  comparison  of 
the  relative  and  absolute  duration  of  these  periods  with  those  of  the  fatigued 
muscles.  Each  tenth  contraction  may  be  recorded  on  one  side  of  the  drum  and 
everp  one  on  the  other,  in  order  to  show  clearer  results.  State  the  characteristic 
features  of  each.  To  get  the  tenth  contraction,  put  in  a  key  and  get  on  one  side  of 
the  drum  ever}' contraction;  on  the  other,  exclude  all  but  the  tenth  M.  and  B.  with 
the  key  at  the  pi-oper  time. 

(b).     Get  a  fatigue  curve  by  stimulating  after  a  rest  of  ten   minutes.   Conclusion? 

Expt.  XCIV.  Contraction  Curves  of  Human  Skeletal  muscles. 

(a)  Istonic.  Place  the  little,  ring,  and  middle  finger  in  the  support  of  the  ergo- 
graph.  Let  the  rod  rest  on  the  index  finger  near  the  distal  end  of  the  middle 
phalanx.  Place  the  rod  in  the  outermost  hole.  With  a  brass  electrode  covered 
with  moist  cotton,  stimulate  the  adductors  of  the  index  finger  indices  or  interros- 
seous  primus  with  a  single  maximal  break  induction  shock.  Record  the  curves  on  a 
moderately  fast  moving  drum.  Compare  the  curves  with  those  of  a  frog's  skeletal 
muscle  obtained  with  single  break  shocks.  Place  the  arm  electrode  on  the  arm  or 
neck. 

(b)  Isometric  Contractions. 

Place  the  rod  in  the  lowest  hole.  The  movements  of  the  spring  are  so  much  less 
here  that  scarcely  any  of  the  muscle's  energy  will  be  converted  into  mechanical 
motion.  Stimulate  again  with  a  maximal  break  induction  shock.  Compare  the 
isometric  chrve  with  the  isotonic  curve  obtained  in  (»). 

ic).   Artificial  Tetanus. 

Place  the  rod  in  the  upper  (isotonic)  hole.  Stimulate  the  adductor  with  the  tetan- 
izing  induction  current.     Compare  with  the  tetanic   curves  from  the    frog's  muscle. 

(d).     Natural  Tetanus 

Contract  the  abductors  by  voluntary  impulses.  This  also  gives  a  tetanic  curve- 
When  the  natural  tetanus  is  prolonged,  it  may  give  oscillation  of  about  ten  per 
minute, 

(e).     Repeat  {d)  with  the  isometric  arrangement. 

(/").     Fatigue  Curve  of  the  Human  Muscle. 

(^).  Arrange  as  in  (b),  getting  isotonic  curves.  Record  on  a  slowly  moving  drum. 
Contract  the  muscies  voluntarily  every  two  seconds,  keeping  time  with  the  metro- 
nome, until  200  contractions  have  been  made.  State  the  character  of  the  two  fatigue 
curve.  Compare  with  those  from  the  frog.  Where  is  the  stimulus  applied  in 
(/)?     in  U-)? 

(/i).  From  a  fresh  subject,  obtain  fatigue  curves  by  stimulating  the  abductors 
of  the  index  finger  with  a  maximal  M.  and  B  alternately  every  two  seconds, 
obtaining  200  contractions.  « 

(/).  Then  contract  it  voluntarily  every  two  seconds  for  about  200  times.  Compare 
the  curves  with  those  of  the  preceding  experiment. 

What  is  the  difference  between  the  arrangements  (/"and  .5^)  {/i  and  ?)? 

What  object  is  aimed  at?  Which  part  is  fatigued  more  readily,  muscle,  nerve 
ending  or  central  nervous  system? 

Expt   XCV      The  Effect  of  Gradual  Changes  in  Stimuli. 

It  has  been  shown  that  mechanical,  thermal  and  other  forms  of  stimuli  may  be 
so   slowly  applied  to  nerves  or  muscles  that  a  response  will   not   be   called  forth.     Is 


Outlines  of  Experimental  Physiology  73 

this  true  for  electrical  stimulation?  Connect  several  cells  through  a  simple  key 
to  the  lower  binding-  posts  of  Fleischl's  Rheonom,  the  cross  zinc  wires  of  which  are 
freshly  anialg-amated  and  the  furrow  filled  with  concentrated  zinc  sulphate.  From  the 
upper  posts  of  the  Rheonom,  lead  wires  to  the  moist  chamber  which  contains  the  N. 
M  P.  and  set  the  cross  wires  so  that  the  smallest  part  of  the  cells  can  be  sent 
throug-h  the  preparation;  i  e.,  when  the  cross  arms  are  at  rig-ht  ang-les  to  the  lower 
binding-  posts.  Let  the  lever  write  on  a  slowly  moving  drum.  Then  slowly  close 
the  kej'  and  move  the  cross  arms  very  carefully  and  slowly  toward  the  binding-  posts, 
not  letting-  them  quite  touch  them  Now  practically  all  the  current  is  sent  through 
the  preparation.     Slowly  rotate  the  arms  to  their  first  position. 

(b).  Quickl}'  rotate  the  arm  from  the  minimum  to  the  maximum  position. 
Result?     Conclusion? 

Expt.  XCVI.     The  Influence  of  the  Cathode  and  Anode  Poles. 

Curarize  a  frog;  set  up  the  N.  P.  E.,  connect  them  through  a  simple  kej'  and 
pole  changer  to  the  cell.  Pith  the  frog  when  it  is  completely  curarized,  expose  the 
abdominal  rectus  or  both  sartorius  muscle  that  have  been  isolated  from  the  other 
muscles.  Keep  the  frog  moist  and  insulate  the  muscle  with  rubber  tissue.  Place 
the  electrodes  at  the  extreme  end  of  the  rectus  or  at  the  tibial  ends  of  the  sartorius. 
Make  the  current.  Did  the  anode  or  cathode  side  contract?  Break  the  current. 
At  which  pole  did  the  contraction  arise? 

(b).  Reverse  the  poles  again,  make  and  break  the  current  and  note  which 
contraction  was  stronger  and  where  it  began  at  make  and  break.     Conclusion? 

Expt.  XCVII.     Polar  Stimulation  of  the  Heart.     Monopolar  Method. 

This  method  was  suggested  by  the  fact  that  the  stimulation  of  the  galvanic 
current  depends  upon  its  density.  If  one  electrode  has  a  large,  the  other  a  small 
surface,  the  current  lines  will  be  distributed  through  a  considerable  cross  section 
in  the  first  instance,  and  converge  to  a  small  one  in  the  second.  The  threshold  value 
will  not  be  reached  at  the  large  electrode,  and  stimulation  occurs  only  at  the  small 
electrode  which  is  placed  on  the  heart.  The  large  indifferent  electrode  may  be 
placed  on  any  part  of  the  frog.  Connect  one  N.  P.  E.  through'a  Pohl  changer  with 
cross  wires  to  1  / 10  or  more  of  the  current  on  the  rheostat,  connected  through  a  key 
to  a  dry  cell.  Cover  the  large  electrode  with  a  cloth  moistened  with  saline  solution. 
Carefully  expose  the  heart,  tie  a  ligature  around  the  auriculo-ventricular  junction 
to  stop  the  ventricular  contractions.  Turn  the  pole  changer  so  that  the  electrode  on 
the  heart  becomes  the  anode  Close  and  open  the  key.  Contraction  occurs  at  break 
if  at  all.     Why? 

{b).  Reverse  the  pole-changer  so  that  the  cardiac  electrode  becomes  the  cathode. 
Make  and  break  the  current.     Contractions  occur  at  make  only.     Why? 

Expt.  XCVIII.    Electrotonus. 

When  a  nerve  is  traversed  by  a  constant  current  its  vital  properties  are  altered; 
i.  e.,  its  excitability,  conductivity,  and  electro-motivity.  The  region  affected  by  the 
positive  pole  is  said  to  be  anelectrotonic  and  that-by  the  negative,  in  the  kathelectro- 
tonic  condition. 

We  study,  therefore,  (I).  Electrotonic  alterations  of  excitability.  (2).  Conduc- 
tivitj'.  (3).  Elect  romotivit}'. 

Electric  Variation  or  Excitability. 


74  Outlines  of  Experimental  Physiology 

A.  {a).  Connect  two  cells  to  a  commutator  with  civdss  bars,  introducing  a  key 
to  short  circuit  the  battery.  From  two  of  the  binding-  screws,  connect  wires  with 
two  N.  P.  electrodes.     Place  the  free  end  of  the  n^rve  on  these. 

(b)  Place  on  the  nerve  between  the  electrodes  and  the  muscle  a  drop  or  crystals 
of  common  salt.  In  a  minute  the  muscle  begins  to  twitch  and 
gradually  a  more  or  less  complete  tetanus  sets   in. 

(c).  Arrange  the  commutator  with  the  negative  pole  next  the  muscle,  the  muscle 
becomes  tetanic.  The  negative  pole  (kathelectrotonic  area)  increases  the  excita- 
bility. 

[d)  Reverse  the  current,  so  that  the  anode  is  next  to  the  muscle,  Stimulate. 
The  tetanic  contractions  disappear. 

(e).  The  contractions  of  the  muscle  are  to  be  recorded.  Wash  off  the  salt 
solution. 

(/).  Conclusions  regarding  the  influence  of  the  anode  and  cathode  upon 
irritability. 

B.  Electrotonic  Effect  of  a  Constant  Curi-ent  on  Excitability. 

(a),  A  N.  M.  P.  is  fastened  to  a  lever  in  the  moist  chamber  so  that  the  nerve 
lays  across  two  pairs  of  electrodes. 

(a).  The  platinum  electrodes,  placed  next  to  the  muscle,  are  the  stimulating 
ones.  The  nerve  is  to  be  stimulated  with  these  three  times  both  in  the  anodal  and 
cathodal  regions,  before,  during,  and  after,  the  passage  of  a  constant  current.  Thf 
platinum  electrodes,  are  connected  to  the  secondary  coil  of  an  inductorium 
which  must  have  its  short  circuiting  key  closed  or  must  have  a  large  resistance  in- 
troduced into  its  secondary  circuit  to  prevent  the  entrance  of  the  constant  current 
during  the  stimulation.  One  cell  is  joined  through  a  simple  key  to  the  primary, 
coil,  arranged  for  the  weakest  tetanus. 

[b).  In  the  holders  further  from  the  muscle  are  placed  the  N.  P.  E.  joined 
through  a  Pole-changer  to  which  are  connected  two  cells  through  a  simple  key. 
This  is  the  polarizing  current; — by  means  of  it,  the  current  can  be  varied  in  direct- 
ion and  be  put  on  or  off  at  will.  The  record  of  muscular  contractions  is  made  on  a 
stationary  drum  moved  by  hand  for  a  short  distance  after  contraction.  Arrange  the 
pole-changer  so  as  to  bring  the  cathode  nearer  to  the  muscle;  i.  e.,  the  current 
descending  toward  the  muscle  from  the  polarizing  current. 

(1).     Descending  Currents.     Kathode  pole  investigated. 

(a).  Get  the  curves  of  minimal  tetanus  to  use  for  comparison.  Now  close  the 
short-circuiting  key  of  the  secondary  coil. 

(b).     Make  and  Break  the  polarizing  current, 

(c).  Open  the  short-circuiting  key  of  the  secondary  coil  and  while  stimulating 
with  the  induction  current,  at  once  throw  in  the  constant  current,  so  that  the  nerve 
is  stimulated  in  the  cathode  region  at  make. 

{d).  Close  the  short-circuiting  key  of  the  secondary.  Wait  a  few  minutes  then 
with  the  same  strength  of  current  as  in  {b),  make  the  constant  current  and  imme- 
diately after  breaking  the  current,  open  the  short-circuiting  key  of  the  secondary, 
and  stimulate  again  in  the  cathode  region. 

(II).     Investigation  of  the  Anode  Pole.     Ascending  Current. 

Repeat  a,  b,  c,  and  d,  with  the  ascending  current,  both  constant  and  interrupted 
currents  being  of  the  same  strength  as  in  I. 


Outlines  of  Experimental  Physiology  75 

Compare  the  curves  obtained  with  stimulating  electrodes  before,  during  and 
after  the  flow  of  the  polarizing  currents,     Conclusions? 

Expt.  XCIX.     Changes  in  Conductivity. 

The  apparatus  is  arranged  as  in  the  preceding  experiment,  with  the  difference 
that  the  stimulating  electrodes  are  placed  in  the  extra-polar  region,  so  that  both  the 
polarizing  electrodes  are  between  the  muscle,  and  the  electrodes  are  joined  to  the 
inductorium. 

(1).     With  Descending  Polarizing   Currents — The   cathode   next   to   the  muscle. 

(a  .     Obtain  three  minimal  stimulating  curves. 

(b).  Obtain  make  aud  break  polarizing  curves,  the  short-circuiting  key  of  the 
inductorium  closed. 

(c).  Open  the  short-circuiting  key  and  while  stimulating,  at  once  throw  in  the 
polarizing  [current.     Then  short-circuit  again. 

id)-  Wait  a  few  seconds,  then  stimulate  with  the  polarizing  current  and  im- 
mediately after  breaking  the  circuit,  open  the  short  circuiting  key  and  stimulate 
with  the  induction  current. 

(2).   Repeat  a,  b,  c,  and  with  the  ascending  polarizing  current. 

Conclusions  regarding  the  changes  produced  in  conductivity*  in  the  nerve  at  the 
anode  and  cathode  poles. 

B.  Stimulating  Electrodes   in  the  Intrapolar  Region 

Repeat  1  and  2  of  the  preceding  experiment  excepting  that  the  stimulating 
electrodes,  ^ those  joined  to  the  inductorium),  are  both  placed  between  the  polarizing 
electrodes. 

(a)  Descending  Currents.  The  cathode  pole  is  between  the  muscle  and  the 
stimulating  electrodes  while  in  the  (2),  ascending  curve  the  anode  pole  is  between 
the  muscle  and  the  stimulating  electrodes. 

Do  the  results  corroborate  those  obtained  in  (A)? 

C.  Repeat  A.  and  B. ,  removing  the  stimulating  electrodes  entirely  and  in 
their  place,  put  NaCl  crystals  for  the  stimulating  effect.  Obtain  curves  for  a,  b,  c, 
and  d,  both  with  (1)  descending  with  (2)  ascending  currents.     Conclusions? 

We  are  now  in  a  position  to  account  for  the  phenomena  described  by  the  law  of 
contraction.  The  irritibility  and  conductivity  are  altered  in  a  definite  manner  by 
the  Galvanic  current.  State  your  conclusions  regarding  first,  irritability  at  the 
cathode  and  the  anode  at  the  closure  and  opening  of  the  descending  and  ascending 
Galvanic  currents  and  which  is  the  more  effective? 

Second,  conductivity  at  the  cathode  and  anode    at  the  closure    and    opening   of   the 
descending  and  ascending  currents. 

Expt.  C.   Irritability  and  Conductivity  are    Separate  Properties  of   the   Xerve. 

Carbon  dioxide.  Use  a  small  vial  with  holes  blown  through  opposite  sides  and 
cork  with  inflow  and  outflow  tubes  for  CO 2.  and  platinum  electrodes  which  are 
connected  through  a  pole  changer  with  cross  wires  to  an  inductorium  arranged  for 
minimal  interrupted  or  break  shocks.  From  the  remaining  posts  of  the  pole 
changer,  lead  platinum  electrodes  to  the  moist  chamber  for  stimulating  the  distal 
end  of  the  nerve  outside  the  vial.  Draw  the  nerve  carefully  through  the  vial  holes, 
stopping  them.with  claj'.     Let  the  muscle  lever  write  on  a  slow  moving  drum. 

(a).   Stimulate  the  nerve  inside  the  vial. 

{b).   Stimulate  the  nerve  outside  the  vial. 


76  Outlines  of  Experimental  Physiology 

{c).  Pass  CO  2  from  the  generator  (20  per  cent  HCl  on  marble  chips)  through 
the  vial  for  a  few  minutes.  {The  irritability  is  first  affected.  If  the  COg  effect  is 
prolonged,  conductivity  is  als.o  affected).  Then  stimulate  the  nerve  as  before;  in- 
side and  (d)  outside  the  vial.  What  has  been  altered,  the  conductivity  or  irritability 
of  the  nerve? 

(1).   Remove  the  COg  by  blowing  through  the  vial. 

{a).  Stimulate  inside  (b)  outside  of  the  vial.  Obtain  curves.  Place  a  bit  of 
cotton  saturated  with  ether  in  the  vial,  being  careful  not  to  let   it    touch    the   nerve. 

(c(.  Stimulate  the  nerve  inside  the  vial. 

(d).  Stimulate  the  nerve  outside  the  vial. 

{e)  Result?  If  either  effect  is  prolonged  both  irritability  and  conductivity  are 
altered.     Excitability  is  affected  first. 

Note.  From  the  foregoing  experiments,  the  following  Laws  of  Electrotonus  have 
been  deduced. 

[1] .  A  constant  current  increases  the  irritability  in  the  region  of  the  cathode 
(catelectrotonus)  and  decreases  the  irritability  in  the  anode  region  [anelectrotonus] . 

[2].  During  the  passage  of  a  strong  current,  the  conductivity  is  decreased  in 
the  anode  region.  At  the  instant  of  breaking  the  polarizing  current,  conductivity 
is  restored  in  the  anode  and  lowered  in  the  cathode  region. 

Expt.  CI.   Polar  Stimulation  of  Nerves  or  the  Law  of  Contraction. 

Whether  contraction  will  follow  Galvanic  stimulation  of  a  nerve,  depends  first 
upon  the  irritability  and  second,  upon  the  conductivity  of  the  nerve,  third,  upon 
the  intensity  and  fourth,  on  the  direction  of  the  current.  The  current  may  pass 
throtigh  the  intrapolar  portion  of  the  nerve  toward  the  muscle  [descending]  or 
away  from  it  [ascending].  Intensity  may  be  weak,  medium  or  strong,  relative  to 
the  irritability  of  the  particular  nerve  in  hand. 

Effect  of  Ascending  Currents. 

Make  the  N.  M.  P.,  the  femur  in  the  clamp,  place  the  nerve  over  the  N.  P.  E, 
in  the  moist  chamber.  Connect  a  dry  cell  through  an  open  key  to  the  rheostat  join 
the  pole-changer  with  cross-wires  to  the  rheostat  for  weak  currents,  and  to  N.  P,  E. 
Connect  the  tendon  to  the  lever.  Arrange  the  pole-changer  to  have  the  anode  next 
the  muscle  (ascending). 

(a).  Make  and  break  the  current.  Contraction  occurs  at  make.  Note  the 
strength  of  the  current. 

{b).  Repeat  with  the  same  strength  of  current  as  in  {a)  with  the  cathode  next  to 
the  muscle,  (descending).     Result?     Strength  of  current? 

(c).  With  ascending  current,  increase  the  current.  How  much?  Remove  the 
rheostat  if  necessary,  until  a  contraction  occurs  at  both  make  and  break. 

(d).     With  the  ascending  current,  repeat    (c).     Note  the  strength   of   the  current. 

(e).  With  the  ascending  current,  add  a  sufficient  number  of  cells  until  make 
and  not  break  causes  contraction.     Remove  the  rheostat.     Use  more  cells. 

(/■).     Repeat  with  the  descending  current. 

Set  down  the  results  in  a  table  and  state  in  each  case  the  number  of  cells  and 
the  fraction  of  currents  used. 

(i").  Make  out  a  law  for  ascending  and  descending  currents,  known  as  the  law 
of  contraction.     This  explains  the  manner  in  which  the   effects   of   stimulation   of  a 


Outlines  of  Experimental  Physiology  77 

nerve  with  a  constant   current,    vary    with    streng-th    and    direction    of    the  current. 
Recall  some  of  the  previous  results. 

Expt   CII.     Electricity  or  Differences  of  Potential  in  Muscle. 

A.  The  physiolog^ical  rheoscope  or  electromotive  detector. 

Make  a  leg  nerve  preparation.  Lift  the  sciatic  with  a  g-lass  rod  and  drop  it 
quickly  on  the  gastrocnemius  so  that  the  cut  and  longitudinal  parts  of  the  nerve 
touch  it  at  two  places.     Result? 

B.  Lay  the  preparation  on  a  tilted  clean  glass  side.  Place  two  clean,  thin  clay 
pads  moistened  in  normal  NaCl  solution,  over  the  edge  of  the  glass,  quite  close 
together.  Put  the  cut  edge  of  the  nerve  against  one  pad  and  the  longitudinal  side 
of  the  nerve  against  the  other.  Now  quickly  lift  a  watch  crystal  containing  normal 
salt  solution  to  the  overhanging  ends  of  the  clay  pads,  or  filter  paper  moistened  in 
normal  salt  solution  dropped  over  the  ends  of  the  pads.  Notice  the  toes  or  muscles 
at  the  instant  of  closing  the  circuit.     Conclusions? 

(C).  Prepare  a  fresh  N.  M.  P.,  injure  the  tendon  end  of  the  muscle  and  repeat 
(A,.     Result. 

(D).  Place  the  preparation  (C)  on  a  separate  slide  placed  close  to  the  other  on 
which  place  the  N.  M.  P.  of  (B).  Lay  the  nerve  of  (c)  on  platinum  electrodes  joined 
to  an  inductorium  and  the  nerve  of  (B)  on  the  muscle,  (c),  so  that  the  cut  end  is  sep- 
arated from  the  longitudinal  side  of  the  muscle  bj^  a  glass  nerve  lifter,  the  nerve 
touching  the  muscle  at  two  different  points.     Stimulate  (C)  and  note  the  effect  in  (B). 

(a).     What  is  the  effect  of  make  aud  break?     Of  tetanus? 

(^>).  The  nerve  lying  on  the  muscle  whose  nerve  is  directly  stimulated,  is  ex- 
cited by  what  current,  that  of  the  battery  or  by  the  action  current  of   the    muscle? 

(c).     What  portion  of  C  is  traversed  by  the  electric  current? 

(cf).  Does  the  electrical  current  traverse  the  muscle  C  between  the  points  sepa- 
rated b}'  the  nerve-lifter? 

Preparation  B  is  called  a  rheoscopic  frog.  If  the  contractions  are  caused  by 
differences  of  potential  or  electricity,  they  should  be  detected  with  the  galvanometer 
or  electrometer. 

Expt.  cm.     Electrical  Phenomena  in  Muscle. 

A.  Demarcation  Current  in  Muscle. 

Place  small  platinum  electrodes  connected  through  a  short  circuiting  key  to  an 
inductorium  arranged  for  tetanus,  in  the  posts  further  from  the  muscle  and  a  pair 
of  N.  p.  E.  connected  through  a  key  to  a  galvanometer  or  electrometer.  Test  the  N. 
P.  E.  by  placing  the  brushes  in  contact.  If  any  movement  in  the  galvanometer  oc- 
curs, the  N.  P.  E  are  polarized  and  must  be  set  up  again.  Fasten  the  femur  of  the 
N.  M.  P.  in  the  clamp  and  the  injured  tendon  end  pinned  to  a  piece  of  cork  stuck  in 
the  clamp  rod  of  a  moist  chamber. 

(n).  Lay  one  N.  P.  E.  on  the  injured  and  the  other  on  the  uninjured  part  of  the 
muscle,  open  the  key  and  note  the  direction  and  extent  of  movement  of  mercury  or 
the  spot  of  light  on  the  scale. 

(b).  Determine  which  is  the  positive  portion  of  the  muscle,  judging  from  the 
galvanometer  or  electrometer  movements, 

B.  Action  Current  in  Muscle. 

Without  disturbing  the  position  of  the  muscle,  lay  the  nerve  on  the  platinum 
electrodes,  open  the  electrometer    key  and  wait  until  the  mercury  comes  to  rest,  then 


78  Outlines  of  Experimental  Physiology 


stimulate  with  a  weak  tetanus,  the  N.  M.  P.  by  opening!  the  short  circuiting-  key. 
Note  the  direction  and  extent  of  the  movement  of  the  galvanometer  or  capillary  elec- 
trometer and  the  variation  of  current  as  indicated  by  the  galvanometer.  Which  di- 
rection does  the  current  take  in  the  muscle?  Which  is  greater,  the  current  of  injury 
(demarcation)  or  current  of  action? 

[C].     Demarcation  and  Action  Current  in  the  Nerve. 

Repeat  [A]  with  the  nerve  alone,  laying  the  injured  cut  end  on  one  and  the  lon- 
.  gitudinal  side  of  the  neiwe  on  the  electrode. 

(a).  Determine  the  direction  and  (b)  extent  of  the  deflection  in  the  galvanometer, 
and  [c]  the  direction  of  the  current  in  the  nerve. 

[D].  Repeat  [B].  Is  the  action  current  greater  than  the  demarcation  current 
in  the  muscle  or  in  the  nerve? 

Expt.  CIV.     Contraction  of  Human  Muscles. 

Arrange  the  inductorium  for  single  shocks  with  one  cell  and  key  in  the  primary 
circuit.  Determine  the  cathode  pole  of  the  secondary  coil  when  the  primary  current 
is  broken  through  the  galvanometer.  To  this  pole,  connect  the  small  electrode;  to 
the  other,  the  lai"ge  one.  Cover  both  with  a  cotton  cloth  wet  with  saline  solution. 
The  smaller  place  over  the  nerve,  the  larger  on  an  indifferent  region,  as  the  arm  sto- 
mach or  neck.  With  the  smaller  electrode  make  out  on  anterior  and  posterior  side  the 
motor  points  [where  the  nerve  enters  the  muscle]  of  the  arm  muscles, — anterior  sur- 
face, Lumbricales,  Digiti,  Pollicis,  Flexor  Pollicis  Longus,  Ulnaris,  Radii,  Pro- 
nator radii  teres  Posterior  Surface.  Interosseous,  Abductor  minimi  digiti.  Extensor 
pollicis  longus  add  brevis.  Extensor  communis  digitorum,  Extensor  radii  longus. 
Make,  then  break  the  current.  Does  contraction  follow  at  make  or  break  at  anode 
or  cathode?     Illustrate  the  points. 

Polar  Stimulation  of  Human  Nerves.  Connect  terminal  zinc  and  carbon  of  8 
cells  in  series  through  a  pole  changer  with  cross  wires,  to  a  small  and  a  large  elec- 
trode covered  with  cotton  moistened  with  NaCL.  Place  the  small  electrode  over  the 
ulnar  nerve  between  the  internal  condyle  and  olecranon  a  little  above  the  furrow. 
Make  and  break  the  current,  add  cells  up  to  12,  never  more  than  16  until  contraction 
occurs. 

(a).  Cathode  over  the  nerve,  first  contraction  at  make.  With  this  strength  of 
current,  break  contraction  will  be  absent. 

{b).  Turn  with  the  pole-changer,  bringing  the  anode  over  the  nerves.  A  strength 
of  current  will  be  reached  with  which  make  will  cause  contraction,  but  not  break- 
(c).  A  slightly  greater  current  will  bring  out  the  anodal  break  contraction.  (Some- 
times anodal  break  precedes  the  make). 

(d).  Further  increase  gives  catliodal  break  contraction  and  may  cause  anodal 
make  tetanus.     Tabulate  the  results. 

Test  the  strength  with  the  milammeter.  [Dose,  2-10  milliamperes] .  For  this 
purpose,  the  milammeter  is  employed.  Remember  the  positive  pole,  the  one  from 
the  carbon  plate  is  joined  to  the  positive  post  of  the  inilammeter  and  the  small  elect, 
rode  to  the  negative  pole  of  the  cell.  Place  the  electrodes  on  the  neck  and  arm  and 
when  the  body  is  in  circuit,  read  off  the  strength  of  the  current  directly  from  the 
scale. 

[/].  Place  the  cells  in  the  circuit  with  the  Voltmeter,  determine  the  voltage 
directly  and  {^)  from  these  data,  calculate  the  resistance  offered  by  the  body. 


Outlines  of  Experimental  Physiology  79 


Expt.  CV.     Anatomj'  of  the  Frog-'s  Brain. 

References, — Wiedersheim,  Ecker,  and  Schenk. 

[1].  Make  a  median  cut  throug-h  the  skin  beginning  at  the  level  of  the  occipi- 
tal artery  and  in  the  skin.  Note  the  cutaneous  artery  imd  vena  magna.  Carefully  lift 
and  remove  the  roof  of  the  skull.  Make  a  careful  drawing  [enlarged]  and  note  the 
relations  of  different  regions  of  the  brain  with  landmarks  of  the  body;  e.  g. ,  eye, 
nares,  tympanum.  Note  the  olfactory  lobes,  cerebrum,  thalamencephalon,  pineal 
body,  cerebellum,  and  medulla.  Note  the  optic,  olfactor3'.  and  other  nerves  as  far 
as  the  eleventh,  given  oft'  from  the  medulla.  Lift  the  optic  lobes  and  see  the 
pituitarj'  body. 

Expt.  CVI.     Excision  of  the  Cerebral  Hemispheres  in  the  Frog. 

Method.  The  following  articles  are  needed  for  the  operation.  Scissors,  scal- 
pel, forceps,  trephine,  silk,  cotton  corrosive,  1  per  cent  adrenelin,  NaCl,  frogboard, 
ether,  and  a  bell  jar.     Sterilize  the  instruments  in  boiling  water. 

When  everything  is  in  readiness,  put  Ic,  c.  of  ether  on  a  small  piece  of 
cotton  on  a  frog  under  the  bell  jar.  Test  the  aft'ect  of  the  anesthesia  by  the  reflex 
of  the  eyes.     How  does  the  anesthesia  affect   the  respiration? 

A.  When  anesthesized  make  a  median  incision  over  the  skull  yi  inch  long 
fasten  back  the  skin  with  pin  hooks,  after  having  washed  the  skin  in  corrosive,  and 
having  fastened  the  animal  to  the  frog-board.  Expose  and  remove  the  cerebrum, 
be  sure  not  to  get  corrosive  in  the  wound  and  to  remove  all  nerve  tissue  in  front  and 
not  to  injure  the  thalamencephalon  and  neighboring  parts.  Use  NaCl  solution  on  the 
wound  and  adrenelin  to  stop  the  bleeding. 

Suture  the  skin  and  wash  in  salt  solution. 

Date  and  note  all  observations  regarding  the  position  and  irritability  during 
and  after  the  shock.  Compare  with  the  normal  frog, — ej'es,  nares,  respiration, 
when  placed  on  its  back  or  on  an  inclined  plane,  in  water,  obstruct  its  path, 
stimulate  its  croak  centre,  by  stimulating  its  side  back  of   the  front  legs. 

Will  it  catch  flies  when  put  in  its  pan? 

After  several  hours,  days  or  weeks,  note  any  furthur  changes. 

What  is  the  conclusion  regarding  the  frog's  cerebrum?     Co-ordination? 

B.  Removal  of  right  Cerebral  Hemisphere. 

With  the  same  precautions  as  observed  in  the  preceding  operation,  remove  the 
right  cerebral  hemisphere  and  sew  the  skin  together. 

Note  and  date  all  the  important  observations  immediately  and  for  hours  and 
days  afterwards.     Keep  the  frogs  in  clean  moist  moss. 

C.  Remove  the  thalamencephalon.     Compare  with   A. 

D.  Pith  a  frog;  i.  e,  remove  the  whole  brain.  State  the  important  differences 
between  A,  C,  D. 

Suggestions.  The  parts  to  be  removed  must  be  clearly  seen  before  thej'  are 
cut.     Notice  the  overlapping  of  the  cerebral  lobes. 

Expt.  CVII.  Reflex  Action  of  the  Spinal  Cord. 

Simple  Reflex. 

Expose  the  brain  and  remove  onl\'  the  part  anterior  to  the  optic  lobes. 

[1].  How  long  before  the  shock  eft"ect  passes  off?  Test  by  pinching  and  posi- 
tion. Note;  position  of  bodj-,  head,  legs,  respiration,  eye  reflex,  croak  reflex,  turn- 
ing-over reflex.     Compare  with  a  normal  animal. 


80  Outlines  of  Experimental  Physiology 

[2] .  Suspend  the  frog-  by  its  upper  jaw  in  a  clamp.  Does  this  stimulate? 
Why  not? 

[a].     Pinch  one  foot,  first  gently,  then  increase  the  streng-th.     Result? 

[6].  Hold  the  toe  and  pinch  the  leg.  Result?  Why?  Afferent  and  efferent 
path? 

[c] .  Stimulate  the  leg  with  a  weak  induction  shock  of  such  a  strength  that  sin- 
gle stimuli  cause  no  reflex  contraction.  Stimulation  of  subminimal  stimuli  will 
produce  reflex. 

[3].     Purposive  Character  of  Reflex. 

Dip  4  m.  m.  squares  of  filter  paper  in  20  per  cent  acetic  acid,  others  in  40  per 
cent. 

Place  one  upon  the  flank.  Result?  Wash  the  skin  and  after  a  short  period  of 
rest,  apply  another,  holding  the  leg  of  that  side.  Result?  Wash  the  skin  and  study 
the  effect  bv  altering  the  position  and  strength  of  the  stimulus. 

[4].  Reflex  Time.  Prepare  4  beakers  containing  fresh  water  and  H2SO4  of 
0.1  percent,  0.3  percent,  and  0.5  per  cent.  Arrange  a  signal  with  key,  one  cell  and 
time  marker  to  record  on  a  slow  moving  drum.  Move  one  leg  aside  with  a  glass  rod 
and  let  the  other  dip  into  the  solutions,  beginning  with  the  weakest.  Record  with 
the  signal  the  instant  it  is  withdrawn.  Wash  the  leg  thoroughly  and  allow  a  period 
of'Test  to  intervene  between  each  test.  Tabulate  the  results,  noting  the  relative 
time  and  strength  of  the  stimuli. 

(5] .   Inhibition  of  Reflex  through  Peripheral  Afferent  Nerves. 

Get  the  reflex  time  with  0,1  per  cent  H 2  SO'4.  Expose  the  sciatic  nerve  about 
one  inch,  ligate,  cut,  and  place  the  central  stump  of  the  nerve  on  the  electrodes  and 
stimulate  with  the  weakest  induction  current.  Dip  the  other  leg  in  the  acid  again, 
recording'the 'instant  of  immersion  and  withdrawal  while  the  nerve  is  being  stimu- 
lated. Wash  off  the  acid  thoroughly.  Has  the  latent  period  of  reflex  been 
prolonged?     Why? 

[6] .   Through  Central  Afferent  Paths,  the  Optic  Lobes. 

Expose  the  optic  lobes.  Determine  the  reflex  time  with  0.1  per  cent  or  0.3  per 
cent  H3  SO 4.  Wash  off  the  acid  and  after  a  time  put  NaCl  crystals  on  the  cut  sur- 
face of  the  optic  lobes.  When  the  salt  has  had  an  effect,  determine  the  reflex  time 
as  before.     Has  the  time  of  reflex  been  increased?     Why  ? 

[7].  Place  calcium  chloride  crystals  on  the  lobe  and  determine  the  reflex  time. 
Result?     Conclusions? 

[8].  Place  the  frog  in  water,  wash  off  the  salt  and  remove  the  optic  lobes. 
Again  determine  the  reflex  time.     Has  the  time  been  shortened?     Why? 

Expt.  CVIII.     Reflexes  in  Man. 

Reflexes  play  an  important  part  in  the  maintenance  of  the  human  body  and  a 
disturbance  of  certain  ones  are  of  value  in  the  diagnosis  of  diseases  of  the  central 
nervous  system,  since  the  reflex^depends  upon  the  integrity  of  the  corresponding 
reflex  arc. 

[1].  From  the  Skin.  Rub  the  plantar  surface  of  the  foot  with  a  hard  object. 
The  foot  will  be  retracted. 

[2] .     From  the  eye,  cornea,  and  pupil. 

[3].     Throat  Reflex.     Stimulation  of  the  posterior  wall  causes  swallowing. 


Outlines  of  Experimental  Physiology  81 

[4].  Tendon  Reflex.  Cross  the  leg- and  tap  the  tendon  below  the  patella  with 
the  edg-e  of  the  hand.  The  quadriceps  extensor  muscle  will  be  suddenly  stretched 
and  responds  with  a  quick  contraction  which  throws  the  foot  forward  in  a  kicking 
motion. 

[5] .  Ankle  Jerk.  Bend  the  foot  at  right  angle  to  the  leg  and  strike  the  Tendo 
Achillis.     The  gastrocnemius  contracts. 

Expt.  CIX.     Reaction  Time. 
»[A].     Arrange  a  fast  speed  drum,  time  record  100  per  second. 

Directly  over  the  latter,  place  the  point  of  the  signal.  The  signal  is  connected 
through  a  cell  and  two  keys  to  posts  1  and  2  [shocks]  of  the  inductorium  and  the 
stimulating  electrodes  from  the  secondary  coil  to  the  tongue.  Let  the  subject  close 
his  eyes  and  hold  one  key  closed  until  he  feels  the  stimulus.  The  observer  starts 
the  drum  and  tuning  fork  and  stimulates  by  closing  the  second  key  in  the  primary 
circuit.  Determine  the  interval  between  the  stimulation  and  response.  This  inter- 
val is  the  reaction  time  plus  the  error  of  observation;  e.  g  ,  the  latent  period  of  the 
signal.  Record  briefly  the  links  in  the  chain  between  the  stimulus  and  response 
and  errors  of  observation. 

B.   Reaction  Time  with  Choice 

Connert  the  secondary  posts  with  the  pole  changer  without  cross  bars;  from  one 
set  of  posts  join  wires  to  platinum  electrodes,  from  the  other,  to  neck  and  hand  [brass] 
electrodes.     Tell  the  subject  to  signal  only  when  the  tongue  [or  hand]  is  stimulated. 

Physiological  Optics. 

Expt.  ex.  [a].   Reflection   from  Concave  Mirrors. 

Place  the  2  mm.  diaphragm  in  front  of  the  condenser  in  the  lantern.  Place  the 
concave  mirror  (segment  of  a  5  cm  radius  sphere)  in  the  optical  box  at  right  angles 
to  the  pencil  of  parallel  rays.  The  ra3's  are  reflected  2.5  cm.  from  the  mirror. 
(Smoke  will  make  them  visible).  The  point  to  which  the  parallel  rays  are  converged 
is  the  principal  focus  of  the  mirror.  The  distance  between  the  mirror  and  the 
principal  focus  is  half  the  radius  of  curvature?     Principal  focus? 

{b)  Replace  the  diaphragm  by  an  L  apertured  one;  remove  the  mirror  from  the  box 
and  place  it  in  the  axis  of  the  beam  of  light.  At  the  principal  focus  hold  a  small 
screen  with  a  handle.  Describe  the  image  seen  on  the  screen.  Is  it  erect,  smaller, 
real,  or  virtual? 

(c).  When  the  distance  between  the  mirror  and  object  is  less  than  the  radius 
of  curvature  but  greater  than  the  focal  distance,  state  whether  the  image  is  real, 
inverted  and  the  size  of  the  object.  Are  real  images  from  concave  mirrors  always 
erect  or  inverted? 

(d).  Place  the  mirror  at  less  than  the  focal  distance  from  the  luminous  point. 
Where  is  the  unreal  or  virtual  image? 

(^)  Hold  a  tiny  object  nearer  than  the  principal  focal  distance  to  the  mirror. 
Results? 

(/)  Hold  a  candle  in  front  of  concave  watch  crystals  of  different  curvatures. 
Where  are  the  images  seen?  size?  position  as  compared  with  the  object?  Relation 
of  size  as  compared  with  the  radius  of  curvature. 


82  Outlines  of  Experimental  Physiology 

(^).  Determine  bj'  construction  the  length  of  the  image  of  an  arrow  2  cm.  long- 
placed  10  cm  from  the  middle  point  of  a  concave  watch  cr3'stal5cm.  radius  of  curvature. 

Expt.  CXI.     Reflection  from  Convex  Mirrors. 

[a].  Repeat  Expt.  c,  replacing  the  concave  with  the  convex  mirror.  State  the 
[a]  size,  [b]  position,  [c]  form  of  the  image  as  compared  with  the  object. 

[6].  Determine  by  construction  the  length  of  an  image  of  an  arrow  2  cm.  long 
placed  10  cm.  from  the  middle  point  of  a  convex  mirror  of  5  cm.  radius. 

[c].  Hold  a  candle  in  front  of  convex  watch  crystals  of  difi'erent  degrees  of  cur- 
vature. Describe  the  change  in  size,  position,  and  whether  erect,  and  other  changes 
as  compared  with  the  object  and  the  curvature  of  the  mirror. 

Expt.  CXII.     Refraction  by  Convex  Lenses. 

[a].  Principal  Focus.  Place  the  biconvex  lens  5  cm.  from  the  window  of  the 
box,  parallel  rays  are  brought  to  a  focus  10  cm.  from  the  lens.  The  2mm.  diaphragm 
is  in  the  lantern.  Place  the  black  wooden  screen  at  this  point.  A  real  image  of  the 
diaphragm  aperature  is  seen.     Where  is  the  principal  focus  of  the  biconvex  lens?- 

[b],     E.stimation  of  the  Principal  Focal  Distance. 

Remove  the  tube  of  projection  lenses  from  the  lantern.  Place  in  front  of  the  con- 
densing lens  the  L  diaphragm.  Place  the  convex  lens  in  the  axis  of  the  pencil  of 
rays  at  a  place  greater  than  the  focal  distance.  On  the  other  side  of  the  lens,  place 
a  screen  where  it  will  give  a  clear,  enlarged  image  of  the  L.  Note  the  distance  of 
the  lens  from  the  image  [?].  Is  it  erect  or  inverted?  Note  the  distance  of  the  object 
from  the  lens  [o].  An  easy  method  of  determining  the  focal  distance  of  a  lens  de- 
pends upon  the  relation  of  the  distance  o  the  conjugate  foci  to  the  general  focal 
distance.  This  relation  may  be  expressed  thus; — The  sum  of  the  reciprocals  of  the 
conjugate  foci  equals  the  reciprocal  of  the  focal  distance. 

The  distance  of  the  object  [o]  represents  one  and  that  of  the  image  [z] ,  the  other 
of  these  conjugate  focal  distances;  so  one  maj'  say,  the  reciprocals  of  the  distance 
of  the  object  from  the  lens  l/o  equals  the   reciprocal  of   the   general   focal  distance 

T7  oi 

1 /F,  Study  the  general  formula,  l/o  plus  1  /i  =   l/F.   r  = 

o  +  i 

Determine  o  and  i  f or  several  lenses  and  substitute  their  values  in  the  equation. 
"When  the  object  is  twice  the  focal  distance  what  is  the  distance  of  the   image? 

2.  When  the  distance  of  the  object  is  greater  than  2F  how  does  the  distance  of 
the  image  compare  with  2F? 

3.  When  the  object  is  at  a  very  great  distance  [ow=qo]  at  what  distance  will 
the  image  be  formed?  The  principal  focal  distance  of  a  double  convex  lens  is 
approximately  equal  to  the  radius  of  the  curvature. 

Expt.  CXIII.  Conjugate  Foci. 

Place  the  2  mm.  diaphragm  in  the  lantern,  the  tube  removed,  the  convex  lens 
against  the  window  of  the  box,  and  the  black  screen  twice  the  focal  distance  ©f  the 
lens.  Get  a  clear  image  on  the  screen,  Points  from  which  rays  diverge  and  con- 
verge again  after  passing  a  lens  are  conjugate  foci.  Measure  the  distance  of  the 
luminous  aperture  from  the  lens.  It  will  be  twice  the  focal  distance.  When  the 
point  of  diverging  rays  is  twice  the  focal  distance  from  the  lens,  the  point  of  conver- 
gence is  equally  distant  from  the   lens. 

Move  the  lantern  further  from  the  lens.  The  conjugate  focus  will  approach 
the  lens.     As  one  conjugate  focus  recedes,  the  other  approaches  the  lens. 


Outlines  of  Experimental  Physiology  83 

Virtual  ImcOge.  (a;.  With  the  tube  removed  and  the  2  mm.  diaphrafrm  in  the 
lantern,  the  convex  lens  at  a  distance  from  the  luminous  point  less  than  the  princi- 
pal focal  distance,  one  sees  the  diverging-  rays  passing  through  the  lens  continue  to 
diverge;  but  prolonged  backwards  would  unite  in  a  virtual  imag^  on  the  same  side 
as  the  luminous  object.  The  virtual  image  is  further  fr6m  the  lens  than  the  object, 
is  never  inverted,  and  always  enlarged. 

[b] .  Look  through  the  convex  lens  at  printed  words  placed  between  the  lens  and 
its  principal  focus.     The  image  is  virtual  and  enlarged. 

Expt  CXIV.     Construction  of  Images  Obtained  with  Convex   Lenses. 

Draw  a  horizontal  line  through  the  optical  centre  of  the  lens  of  10"  aperture,  (a 
lens  of  such  curvature  that  parallel  rays  will  be  refracted  through  the  principal 
focus  only  when  the  aperture  of  the  lens  does  not  exceed  approximately  IQO)  and  5 
cm.  radius.  The  radius  of  curvature  being  5cm. ,  the  principal  focus  will  lie  ap- 
proximately Scm.  from  the  optical  centre.  Draw  through  the  optical  centre  a  line 
10  mm.  long,  connect  its  ends  with  the  principal  focus.  The  angle  included  will  be 
about  10",  At  anj'  distance  greater  than  5  cm.,  draw  a  10  mm.  arrow  bisected  by 
the  principal  axis.  Draw  incident  rays  from  the  ends  of  the  arrow  parallel  to 
the  principal  focus.  From  each  end  of  the  arrow  draw  a  line  through  the  optical 
centre  of  the  lens.  Theintersectionofthe.se  lines  mark  the  limits  of  the  imao-e. 
Note  that  it  is  real  and  inverted.  If  the  object  is  twice  the  focal  distance  from  the 
lens,  the  image  will  be  the  size  of  the  object;  if  at  less  than  twice  the  focal  distance 
the  image  will  be  larger  than  the  object;  if  at  more  than  twice  the  focal  distance 
smaller  than  the  object;  if  between  the  principal  focus  and  the  lens  the  image  will 
no  longer  be  real  but  virtual  and  larger  than  the  object. 

Expt.  CXV.     Refraction  by  Concave  Lenses. 

Place  a  2mm.  diaphragm  in  front  of  the  condenser.  Let  the  rays  fall  upon  the 
concave  lens.  The  parallel  rays  will  diverge.  Look  through  the  concave  lens  at 
the  printed  words.  The  image  is  virtual,  upright,  and  smaller  than  the  object.  It 
is  nearer  the  leas  than  the  object  and  always  within  the  principal  focus. 

Expt.  CXVI.     Preparatory  Experiment  For  Purkinji  Sanson  Images. 

Place  a  large  convex  lens  on  a  table;  hold  a  watch  crystal  in  the  left  hand  in 
front  of  the  lens  and  a  few  inches  from  it.  Movj  a  lighted  candle  at  the  side  of  this 
arrangement  and  observe  the  three  images.  Substitute  a  convex  lens  of  shorter 
focus,  observe  the  change  in  the  reflected  images.  Explain  the  phenomena,  using 
drawings 

Purkinji  Sanson  Experiment.  Hold  a  lighted  candle  to  one  side  of  the  observed 
eye  in  front  and  on  a  level  with  it.  Look  obliquely  at  it.  Ask  the  person  to  look  at 
a  distant  object  (far  accommodation)  and  look  into  his  eye  frcm  the  opposite  side  of 
the  candle,  notice  the  relation  in  size  and  position  of  the  three  images.  At  the  mar- 
gin of  the  pupil  and  superficially,  an  erect  image  is  reflected  from  the  anterior  sur- 
face of  the  cornea  In  the  middle  of  the  pupil  is  a  second  less  bright  erect  image 
which  appears  to  lie  further  back.  It  is  reflected  from  the  anterior  surface  of  the 
lens.  The  third  image  lies  toward  the  opposite  margin  of  the  pupil.  It  is  the 
smallest  and  inverted  and  is  furthest  back.  It  is  reflected  from  the  posterior 
surface  of  the  lens. 


84  Outlines  of  Experimental  Physiology 

Expt.  CXVII.     Refraction  by  Segments  of  Cylinders. 

Place  in  the  optical  box  the  2mm.  diaphrag-m  in  front  of  the  condenser.  Throw 
a  pencil  of  parallel  rays  into  the  box.  Place  the  cylindrical  lens  in  the  axis  of  the 
pencil  in  such  a  position  that  the  curvature  shall  be  from  side  to  side;  i.  e  ,  in  the 
horizontal  meridian.  The  image  of  the  circular  aperature  in  the  diaphragm  will 
be  a  vertical  line  with  blurred  convex  ends. 

(b).  Turn  the  cylinder  so  that  the  curvature  shall  be  in  the  vertical  meridian. 
"What  is  the  image?     Illustrate. 

{c).  Astigmatic  Lens.  Place  the  diaphragm  with  the  horizontal  slit  in  the 
lantern,  throw  parallel  rays  into  the  box.  Place  the  cylinder  in  the  axis  of  the  pen- 
cil with  its  curvature  vertical.  The  horizontal  line  is  a  fusion  of  illumined  points. 
From  each  point  rays  diverge  in  all  directions.  Those  passing  from  any  point  in 
vertical  planes  through  the  cylinder,  converging  in  the  vertical  meridian,  will  be 
focused  by  the  convex  surfaces  in  the  corresponding  point  in  the  image.  The  over- 
lapping of  such  points  will  form  a  horizontal  line  with  clear  upper  and  lower  edges. 
The  rays  passing  from  any  point  in  the  illuminated  line  in  horizontal  planes  through 
the  cylinder  with  vertical  curvature,  will  be  refracted  by  plane  glass  surfaces  and 
will  not  come  to  a  point  but  will  form  a  faint  horizontal  line.  The  overlapping  of 
the  imcLge  of  the  bright  points  which  unite  the  rays  passing  in  vertical  planes  and 
the  faint  horizontal  lines  formed  by  the  rays  passing  in  horizontal  planes  will  form 
upon  a  screen  a  horizontal  line  with  blurred  ends. 

(d).  Place  the  vertical  slit  in  front  of  the  condenser.  Draw  a  diagram  illus- 
trating the  formation  of  the  image. 

(e).  Turn  the  cylinder  so  that  the  curvature  will  lie  in  the  horizontal  meridian. 
Into  what  images  are  the  horizontal  rays  united? 

(/).  Astigmatism.  Draw  on  a  card  two  lines  of  equal  thickness  intersecting' 
each  other  at  right  angles.  Fix  it  vertically  at  the  limit  of  accommodation  and  look 
at  it.  Probably  either  the  vertical  or  the  horizontal  line  is  seen  more  distinctly. 
Test  each  eye  separately.  The  line  most  distinct  corresponds  to  the  meridian  of 
least  curvature  of  the  cornea. 

Expt.  CXIII.  Myopia. 

Let  parallel  rays  pass  through  the  convex  lens  (condenser)  of  about  10  cm. 
focal  distance,  and  the  focusing  lens  placed  against  the  window  of  the  optical  box. 
Find  the  principal  focus  and  then  move  the  screen  2.5  cm.  further  away  from  the 
lens.  The  image  is  blurred.  The  screen  will  intersect  the  rays  diverging  from 
the  focal  point.  Hold  the  weak  concave  lens  (1-2)  in  front  of  the  window.  The 
lens  has  a  focal  distance  of  two  diopters  or  j4  metre.  If  the  image  is  clear,  the 
myopia  in  this  case  is-"2D.  Note  the  numbering  of  the  lens.  Lenses  are  numbered 
according  to  their  refractive  power.  The  unit  is  a  lens  with  a  focal  distance  of  one 
metre  (one  diopter,  ID).  A  lens  of  two  metres  focus  is  )i  the  refractive  power  or 
0.5D.  Lenses  ordinarily  employed  in  ophthalmic  practice  extend  from  0.12D  to  22 
D.  The  principal  focal  distance  of  any  lens  in  the  dioptric  system  may  be  found 
by  dividing  one  metre  (100  cm,)  by  the  number  of  dioptrics.  For  example,  4D=^100X 
=25cm.  Convex  lenses  are  positive,  concave  negative  and  they  are. marked  -j-or— . 
When  two  or  more  lenses  are  placed  together,  the  dioptric  power  of  the  system 
thus  formed  equals  the  algebraic  sum  of  the  dioptric  powers  of  the  lens  in  the 
system. 


Outlines  of  p]xperimental  Physiology  85 


Expt.  CXIX.  Hypermetropia. 

Have  the  condensing  lens  in  the  lantern.  Find  the  focal  distance.  Place  a 
white  screen  2  ocm.  nearer  the  lens  than  the  principal  focus.  The  image  will  be 
blurred.  The  screen  will  intersect  the  rays  before  they  have  converged  to  the 
focal  point.  Hold  the  weak  convex  lens  marked  -\-2  in  front  of  the  window.  The 
image   will  be   clear.     The   hypermetropia,  is  therefore,    in  this   case,  ^2D, 

Expt.  CXX.  Chromatic  Aberration. 

(a).  Make  a  pin  hole  in  a  black  card.  Behind  the  hole  place  the  cobalt  glass. 
Look  at  a  white  flame  through  this  arrangement.  Cobalt  glass  allows  violet  and 
red  rays  to  pass  Accommodate  for  violet  by  approaching  the  light  about  30  inches. 
What  does  the  flame  s  how. 

(b).  Accommodate  for  the  red  by  receding.  The  center  of  the  flame  is  what 
color?  What  is  the  halo?  What  is  the  diff"erence  in  distance  for  the  red  and  blue 
focal  images. 

(c).  Each  spectral  ray  due  to  the  difference  in  wave  length  and  rate  of  vibra- 
tion, on  entering  a  refracting  medium,  pursues  its  own  path  and  its  own  principal 
focus.  In  other  words,  the  images  for  the  several  spectral  colors  do  not  coincide 
precisely.  Violet  crosses  nearest  the  lens,  then  blue,  green,  yellow,  orange  and  red. 
The  peripheral  part  of  a  lens  refracts  rays  parallel  to  the  principal  axis  more 
strongly  than  the  axial  portion.  Hence  chromatic  aberration  increases  with  the 
aperture  of  the  lens. 

(d).  Put  the  ground  glass  plate  and  the  diaphragm  with  the  2  mm.  aperture  in 
front  of  the  condenser.  Let  the  raj^s  from  the  illuminated  spot  of  ground  glass  pass 
through  the  lOD  lens  placed  about  15  cm.  in  front  of  the  ground  glass,  i.  e.,  a  distance 
somewhat  greater  than  the  focal  distance  of  the  lens  (10  cm.).  Place  a  white  screen 
about  15  cm.  in  front  of  the  lens.  The  image  of  the  white  spot  upon  the  ground  glass 
will  be  a  disc  with  a  violet  center  and  a  red  margin.  It  is  best  seen  in  a  darkened 
room. 

(e).  Remove  the  white  screen  further  from  the  lens.  At  a  distance  of  about  30 
cm.,  the  center  of  the  image  and  its  border  will  change;  in  what  respect?  The  im- 
age in  this  experiment  is  blurred  because  the  rays  which  pass  through  the  peripher- 
al portion  of  the  lens  cross  the  principal  axis  sooner  than  the  rays  which  pass 
through  the  axial  portion.  If  the  screen  be  placed  at  the  focus  of  the  more  axial 
rays,  this  focal  point  of  the  image  will  be  surrounded  by  dispersion  circles  made  of 
the  rays  which  have  been  refracted  from  the  periphery  through  foci  nearer  the  lens 
and  which  are  now  diverging  from  their  foci.  If  the  screen  be  placed  at  the  princi- 
pal focus  for  the  peripheral  rays,  this  focal  point  will  be  surrounded  bj'  dispersion 
circles  made  by  rays  that  have  not  yet  converged  to  the  principal  axis. 
The  aberration  is  avoided  by  a  diaphram. 

{/)      Place  a  strip  of  red  and  one  of  blue  3  mm.  apart   on   a   black  background. 
Look  intently,  first  at  one,  then  at  the  other.     Which  appears  nearer?     Why? 

Expt.  CXXI.  Place  the  2mm.  diaphragm  in  front  of  the  condenser.  Throw 
parallel  raj's  into  the  box  Set  in  the  box  near  the  window,  a  cj'linder  bottle  filled 
with  water  (refracting  cylinder).  Show  into  what  kind  of  a  focal  image 
the  circular  pencil  of  parallel  rays  are  brought.  Note  the  outer  rays 
of  the  pencil  pass  through  the  outer  part  of  the  cylinder  and  are  therefore 
more  strongly  refracted  than  those  nearer    the    optical    axis.     Each    refracted  ray 


86  Outlines  of  Experimental  Physiology 

intersects  the  refracted  rays  nearer  than  itself  to  the  principal  focus.  These  inter- 
sections form  two  curved  surfaces  extending  from  the  principal  focus  (in  this  case 
not  a  point)  toward  the  cylinder.  Place  a  wire  on  the  side  of  the  bottle.  This 
throws  a  shadow  on  the  opposite  side  showing  the  crossing  of  the  rays. 

{b).  The  curvature  of  the  caustic  surface  will  be  more  noticeable  if  the  2mm. 
diaphragm  is  placed  over  the  aperature  in  the  box  and  light  from  the  lantern  is 
concentrated  on  it  and  then  diverging  raj's  from  this  pass  through  the  cylinder. 

Expt.  CXXII.  Accommodation,  Have  a  person  look  at  a  distant  object.  The 
parallel  rays  of  light  proceeding  from  it,  are  focused  on  the  retina.  Observe  his 
eye  from  the  side  and  somewhat  from  behind  Half  of  the  pupil  projects  beyond  the 
margin  of  the  cornea.  Have  him  look  now  at  an  object  about  six  inches  from  the 
eye,  without  moving  the  eye-ball.  The  rays  of  the  near  object  are  divergent,  yet 
are  also  focused  on  the  retina  with  a  consciousness  of  a  distinct  effort.  The  power 
of  voluntarily'  bringing  divergent  rays  to  a  focus  on  the  retina  is  termed  accommoda- 
tion. Note  that  as  he  looks  at  the  near  object  that  the  whole  pupil  and  a  part  of 
the  iris  next  the  observer  are  projected  forward  owing  to  the  increased  curvature  of 
the  anterior  surface  of  the  lens.     This  requires  careful  observation. 

Expt.  CXXIII.     Scheiner's  Experiment 

Prick  two  smooth  holes  in  a  card  at  a  distance  of  1mm.  from  each  other;  i.  e., 
less  than  the  diameter  of  the  pupil  Fix  two  pins  in  a  cork.  Place  the  pins  in  line 
with  the  holes  on  a  strip  of  wood,  one  about  8  in.  the  other  2U  in.  from  the  card. 
The  latter  maj'  be  turned  horizontally',  turning  the  card  so  that  the  holes  lie  hori- 
zontally or  verticall}'  according  to  whether  the  vertical  or  horizontal  needle  is  to 
appear. 

(1.)  Sit  with  the  back  to  the  window,  close  or  bandage  one  eye  and  with  the 
other  look  through  the  holes  placed  horizontally  at  the  near  pin  which  will  be  seen 
distinctly;  the  far  pin  will  appear  double,  both  images  being  somewhat  dim. 
Move  the  eye  away  and  the  two  images  separate.  Move  the  eye  closer  and  they  ap- 
proach. 

(2).  With  the  other  card  while  accommodating  for  the  near  pin,  close  the  right 
hand  hole,  the  image  disappears;  close  the  left  hand  hole  and  the  left  image 
disappears. 

(3).  Accommodate  for  the  far  pin  the  near  pin  appears  double.  Close  the  right 
hand  hole  and  the  left  hand  image  disappears.  Close  the  left  hand  hole  and  the 
right  hand  image  disappears.  Move  the  eye  gradually  away  and  the  images  -ap 
proach  each  other,  while  on  moving  the  eye  toward    them,  they  separate. 

(4).  Explain  the  phenomena,  drawing  figures  which  show  just  what  must 
take  place  in  the  eye  for  all  experiments. 

(a).  When  the  eye  is  accommodated  for  the  far  point,  why  the  images  approach 
each  other  when  the  needle  is  moved  away  from  the  eye. 

{b).  Why  the  images  separate  when  moved  toward  the  eye. 

(c).  When  the  eye  is  accommodated  for  a  point  nearer  than  the  needle  (near 
point),  why  the  images  separate  when  the  needle  is  moved  away  from  the  eye 

{d).  Why  the  images  approach  each  other  when  the  needle  is   moved  toward   the 

eye. 

(e).  Why  closing  one  of  the  holes  does  not  effect  the  image. 


Outlines  of  Experimental  Physiology  87 


(b).  Why  stopping- one  of  the  holes  when  the  eye  is  focused  at  a  greater  dis- 
tance than  that  of  the  needle,  causes  the  image  of  the  opposite  side  of  the  field  to 
disappear. 

(ff).  If  tlie  eye  is  focused  for  a  shorter  distance,  the  image  of  the  same  side  as 
the  blocked  hole  disappears. 

Expt.   CXXIV.   Determination  of  Near  and  Far  Points. 

(a).  Cut  two  corks  so  that  they  slide  easily  along  a  ruler.  Mount  a  needle  ver- 
tically in  one  cork  and  a  card  with  two  holes  in  a  horizontal  line  in  the  other  cork. 
Place  the  needle  about  25  cm.  from  the  card.  Close  one  ej'e.  Look  through  the  two 
holes  as  in  Scheiner's  experiment;  and  when  one  distinct  image  of  the  needle  is 
seen,  gradually  bring  the  needle  toward  the  card.  Observe  that  it  becomes  double 
at  a  certain  distance  from  the  eye.  Why?  This  is  the  near  point  of  accommodation. 
Make  several  trials  and  measurements  of  the  distances  from  the  needle  to  the  eye 
when  the  doubling  appears.     Record  the  average. 

(b).  Determine  in  a  similar  manner  the  near  point  with  a  horizontal  needle  and 
card  with  the  holes  vertical.  The  average  measurements  of  (a)  and  (b)  may  differ. 
Why? 

{c).  Stand  six  metres  in  front  of  a  card  of  Snellen's  test-types.  If  you  see  the 
numbers  VI  clearly,  the  acuteness  of  vision  is  normal  and  the  far  point  (punctum 
remotum)  is  infinite. 

If  you  read  I  at  one  meter,  II  at  two,  but  cannot  read  VI  at  six  meters,  bring 
the  test  card  toward  the  eye  until  VI  are  seen  clearly.     This  is  the  far  point. 

Expt.  CXXV.     Diffusion. 

(a).  Close  one  eye.  Hold  a  pin  upright  before  the  other  eye  and  gradually 
bring  it  nearer.  When  the  pin  is  from  12  to  i5  cm.  from  the  ej'e,  a  change  in  dis. 
tinctness  will  be  observed.     Of  what  character?     Why? 

{b).  Prick  a  smooth  hole  in  a  card.  Arrange  the  pin  at  the  proper  distance  to 
obtain  the  previous  diffusion  effect  and  introduce  the  card  'between  the  pin  and  the 
ej'e  and  look  through  the  hole  in  the  card.  Distinctness?  Apparent  size  of  the  pin? 
Explain  and  make  constructions. 

Expt.  CXXVI.     Identical  Points. 

{a).  Having  both  e3-es  open,  hold  a  pencil  a  foot  from  them  and  look  at  a  dis- 
tant object  The  pencil  appears  double.  Close  one  eye.  Which  image  disappears? 
Why?  Close  the  left.  Which  image  disappears?  Why?  Reverse  the  experiment 
by  accommodation  for  the  near  object.  The  far  object  will  appear  double.  Close 
one  eye.  Which  image  disappears?  This  experiment  is  easiest  done  by  having  one 
object  20  to  30  cms.  from  the  eye  and  the  other  45  to  60  cms.  awaj'. 

(b).  Look  at  a  near  object  and  then  press  one  eye  ball  out  of  place.  The  object 
appears  double.     Why? 

Expt.  CXXVIT.     Macula  Lutea  or  Yellow  Spot. 

Close  the  eyes  for  a  minute,  open  them  and  while  holding  a  bottle  of  chrome- 
alum  solution  between  one  eye  and  a  white  cloud,  look  through  the  solution.  An 
elliptical  spot,  rosy  in  color,  will  be  seen  in  the  otherwise  greenish  field  of  vision. 
The  size  of  the  spot  depends  on  the  distance  to  which  it  is  projected.  The  pigment 
in  the  yellow  spot  absorbs  the  blue-green  rays,  hence  the  remaining  rays,  red  and 
greenish  blue  which  pass  through  the  chrome-alum,  give  a  rose  color. 


88  Outlines  of  Experimental  Physiology 

Expt.  CXXVIII.     Purkinji's  Figures  (of  the  Retinal  Blood-vessels). 

In  a  dark  room,  hold  an  electric  lig"ht  at  the  level  of  the  nose  at  the  malar  pro- 
cess and  stand  in  front  of  a  monochromatic  wall.  While  looking  steadily  with  one 
eye  toward  the  wall,  accommodate  the  eye  for  a  distant  object,  hold  the  light  close  to 
the  side  of  that  eye  well  out  of  the  field  of  vision,  downwards  and  laterally  from  the 
eye  and  move  the  light  up  and  down.  It  is  better  to  direct  the  eye  outwards,  keep- 
ing it  accommodated  for  a  distant  object.  Ere  long,  dark,  somewhat  red-brown 
branching  lines,  shadows  of  the  retinal  blood-vessels,  will  be  seen  on  a  black  back- 
ground, due  to  the  shadows  cast  by  the  retinal  vessels  on  the  percipient  parts  of  the 
retina.  Therefore,  the  parts  of  the  retina  stimulated  by  light  must  lie  behind  the 
retinal  blood-vessels.  If  the  light  be  moved  in  a  vertical  plane,  the  shadows  move 
upward  or  downward  with  the  light,  but  apparently  opposite.  If  the  light  be 
moved  horizontally  the  shadows  move  in  an  opposite  direction,  but  apparently  in 
the  same  direction 

Modified  Method  for  the  Purkinji's  Figures. 

Concentrate  a  beam  of  sunlight  by  a  lens  on  the  sclerotic  at  a  point  as  far  as 
possible  from  the  corneal  margin,  passing  the  rays  through  a  parallel-sided  glass 
bottle  filled  with  alum  solution  to  sift  out  the  low  heat  rays.  The  eye  is  turned 
toward  a  black  ground.  The  field  of  vision  takes  on  a  bronzed  appearance  and 
the  retinal  vessels  stand  out  on  a  dark  net-work  which  appears  to  move  in  the  same 
direction  as  the  spot  of  light  on  the  sclerotic,  The  area  of  the  yellow  spot  is  devoid  of 
shadows.     Illustrate. 

Expt.  CXXIX.     The  Eye  as  a  Camera  Obscura. 

From  the  eye  of  an  ox,  remove  the  posterior  part  of  the  sclerotic  and  choroid 
from  a  spot  one  centimeter  in  diameter  near  the  temporal  side.  Cover  the  exposed 
retina  with  a  watch  glass.  Turn  the  cornea  toward  an  incandescent  light.  Move 
a  pencil  in  front  of  the  light  in  different  directions  and  note  the  movement  of  the 
shadow  upon  the  retina.  What  kind  of  an  image  is  cast  upon  the  retina,  erect  or 
inverted? 

Expt.   CXXX.   Perimetry. 

Object:— To  test  the  limits  of  indirect  vision.  In  direct  vision  the  image  of  an 
object  falls  upon  the  fovea  centralis.  In  indirect  vision,  the  image  is  formed  on  the 
peripheral  part  of  the  retina. 

Method.  Turn  the  semicircle  horizontally  and  place  the  chart  on  the  brass 
disc,  right  side  up,  with  the  chart  surface  toward  the  reader.  Fasten  concentri- 
cally by  the  two  screws.  Charts  are  labeled  right  and  left  for  the  use  of  the  right 
or  left  eye  respectively.  Ask  the  subject  to  close  the  left  eye  if  the  reading 
is  to  be  taken  of  the  right  eye  and  to  look  steadily  at  the  revolving  point  of 
the  semicircle  marked  by  a  white  disc,  while  the  chin  is  upon  the  rest,  so  arranged 
that  the  open  eye  is  directly  in  front  of  and  on  a  level  with  the  white  disc.  With 
the  semi-circle  held  steadily  in  the  horizontal  position,  take  the  handle  which 
has  a  white  disc  at  one  end  and  pass  it  along  the  inside  of  the  semicircle,  from  the 
extremity  of  the  right  arm  toward  the  centre  until  it  comes  into  the  area  of  indirect 
vision.  Take  the  reading  at  this  point  and  mark  at  the  same  reading  on  the  small 
scale  on  the  chart.  Turn  the  semi-circle  through  any  desired  meridian  and  as 
above,  get  the  readings  and  record,  thus  plotting  the  area  in  which  a  white  object 
can  be  distinguished  with  that  eye. 


Outlines  of  Experimental  Physiology  89 

(2).  Repeat  the  experiment  for  the  other  eye. 

(3).  Repeat  (1)  and  (2)  for  green. 

(4).  Repeat  for  blue. 

(5).  Repeat  for  red,  using-  in  each  case  the  respective  colored  pencils  for  re- 
cording.    Do  not  let  the  subject  see  the  color.     Bring  it  from  without  inward. 

(6).  Conclusion  regarding  the  field  of  vision  for  a  white  object  to  the  horizontal 
meridian  and  the  outer,  temporal,  and  nasal  side  and  for  which  color  is  the  field 
more  extensive? 

(7).  The  perimeter  is  also  useful  for  mapping  out  defects  such  as  blind  spots. 
As  the  observer  moves  the  white  disc  along  the  arc,  the  subject  may  tell  you  that  at 
certain  points  it  disappears  but  comes  again  into  view  as  you  continue  to  move  it 
further  along.  Then  bv-  shifting  the  arc  into  other  meridians,  these  spaces  ma^'  be 
determined. 

Expt.  CXXXI.  (a).  State  what  happens  in  a  fellow  student's  eye  when  he 
looks  at  far  or  near  objects.     Pupil? 

(b).  State  the  effect  on  the  right  pupil  if  light  falls  into  the  left  eye  only. 
Screen  the  right  eye. 

{c).  The  Blind  Spot.  Make  a  cross  and  a  circle  three  or  four  inches  apart  on 
a  large  card.  Closing  the  left  eye,  hold  the  card  vertically  about  10  inches  from  the 
right  ej'e  and  so  as  to  bring  the  cross  to  the  left  side  of  the  circle.  Look  steadily  at 
the  cross  with  the  right  eye  when  both  cross  and  circle  will  be  seen.  Gradually 
bring  the  card  toward  the  eye,  keeping  the  axis  of  vision  fixed  on  the  cross.  At  a 
certain  distance,  the  circle  will  disappear;  i.  e. ,  when  the  image  falls  on  the  entrance 
of  the  optic  nerve.  On  bringing  the  card  nearer,  the  circle  reappears,  the  cross,  of 
course,  being  visible  all  the  time. 

Expt.  CXXXII.     Mapping  out  the  Blind  Spot. 

(a).  Close  the  left  eye  and  look  steadily  at  a  cross  on  a  sheet  of  paper  held  about 
10  inches  from  the  right  eye.  Place  the  blackened  point  of  a  glass  tube  or  point  of 
pencil  near  the  cross  and  gradually  move  it  to  the  right  until  the  black  becomes  in- 
visible, keeping  the  head  steady  and  the  axis  of  vision  fixed.  Mark  this  spot.  Carry 
the  point  further  outward  until  it  becomes  visible  again.  Mark  the  outer  and  inner 
limits  of  the  blind  spot.  Begin  again  moving  the  pencil,  first  in  an  upward,  then  in 
a  downward  direction,  in  each  case  marking  where  the  pencil  becomes  invisible. 
If  this  be  done  in  several  diameters,  an  outline  of  the  blind  spot  is  obtained. 

(6).     To  Calculate  the  Size  of  the  Blind  Spot. 

Let  f=the  distance  of  the  ej-e  from  the  paper. 

F=the  distance  of  the  second  nodal  point  from  the  retina  (about  15  mm.) 

d=the  diameter  of  the  sketch  of  the  spot  drawn. 

D=the  corresponding  size  of  the  blind  spot. 

d        D 

Then  -^^^  Therefore,  D=Fd/ f. 

Expt  CXXXIII.   Description  of  the  Opthalmoscope. 

A  tilting  mirror  for  reflecting  raj's  into  the  subject's  eye.  A  large  disc  of 
convex  lenses  of  seven  different  dioptric  powers  ranging  from  1  D  to  7  D,  marked 
in  white  figures.  These  are  separated  from  the  eight  concave  lenses  of-1  D  to  -8D 
diopters, — marked  in  red.  A  second  disc  of  two  convex  lenses  16  D  and  0.5  D 
marked  in  red  figure^.     These  can  all  be  rotated  in  fr^^nt  of  the  hol^    in  the   mirror. 


90  Outlines  of  Experimental  Physiology 

By  adding  the  0.5D  to  those  of  the  large  disc  we  can  get  one  or  more  whole  diopters 
with  a  half  diopter.  "With  the  16  D  in  front  of  the  opening  and  rotating  the  lenses 
of  the  large  disc  we  get  as  high  as  23  D  with  the  convex  and  -24  D  with  the  concave 
lenses. 

Ophthalmoscopic  Study  with  the  ArtiHcial  Eye  and  Lantern. 

(1).  Direct  Method, 

Remove  from  the  lantern  the  tubes  holding  the  projecting  lens.  Place  the 
ground  glass  screen  before  the  condenser.  See  that  the  inner  tube  of  the  artificial 
eye  is  drawn  out  to  line  C.  The  eye  is  then  accommodated  for  distant  vision.  Set 
the  eye  on  a  level  with  that  of  the  observer's  near  the  edge  of  the  table.  Place  the 
light  on  the  right  side  of  the  artificial  eye  slightly  behind  it.  Hold  the  ophthalmo- 
scope in  the  right  hand  close  to  the  right  eye  at  a  distance  of  about  SOcm.  from  the 
artificial  eye  and  through  the  mirror's  aperture.  Hold  the  elbow  close  to  the 
side  and  the  head  vertical,  so  that  the  observer's  eye  and  the  artificial  may  have 
the  same  visual  axis.  Keep  reflected  light  on  the  pupil  of  the  artificial  eye. 
With  the  pupil  illuminated  approach  the  artificial  eye  until  the  lens-bearing  disc 
lies  in  the  anterior  principal  focus  (50  mm.  in  front  of  this  eye  and  15.  mm.  in  front 
of  the  cornea  of  the  human  eye).  Artificial  eye  accommodated  for  a  distant  object. 
The  observer's  eye  is  also  accommodated  for  distant  vision.  The  power  of  volun- 
tarily relaxing  the  ciliary  muscle  is  obtained  b}'  practice.  The  observer  should 
try  to  look  through  and  beyond  the  eye  at  some  distant  object  or  place  the  -3D  be- 
fore his  eye.  If  the  observer  be  myopic  or  hypermetropic,  his  refractory  error  should 
be  corrected  by  placing  the  appropriate  lens  before  the  opening  of  the  mirror.  As 
the  eye  is  approached,  the  details  of  the  fundus  will  come  into  view.  Find  the  optic 
disc.  The  image  of  the  branch  of  the  central  artery  and  vein  is  virtual  and  magni- 
fied about  16  times  and  erect.  The  apparent  size  of  an  object  held  10  inches  from 
the  eye  would  give  a  retinal  image  1.5  mm.  (the  size  of  the  optical  disc)  which  can 
be  found.     B,  apparent  size  of  the  optic  disc. 

B:1.5::250:1S. 

10  inches=250  mm. 

B  2  5^0  1.5.  B=25  mm. 

(2).     Indirect  Method. 

Arrange  the  light  and  artificial  eye  as  directed  for  the  examination  by  the  direct 
method.  Hold  the  ophthalmoscope  30  cm.  from  the  artificial  eye.  With  the  other 
hand  hold  a  convex  lens  20  D,  at  its  own  focal  length  of  50  mm.  in  front  of  the  cornea. 
The  rays  returning  from  the  fundus,  pass  through  this  lens,  and  form  an  image  in 
the  air  between  the  observer  and  the  lens.  Examine  this  image  through  a  mag- 
nifying glass  of-)-5D  placed  behind  the  aperture  of  the  mirror.  If  the  observer  be 
myopic,  in  moderate  degree  the  aerial  image  will  be  near  his  far  point  and  he  will 
need  no  magnifying  or  correcting  glass;  if  the  myopia  be  excessive,  a  weak  concave 
glass  should  be  used.  If  the  observer  be  hypermetropic,  the  degree  of  his  hyper- 
metropia  should  be  added  to  the  focal  distance  of  the  magnifying  glass.  The  con- 
fusing bright  reflexes  from  the  surface  of  the  2D  lens  may  be  avoided  by  holding  the 
lens  slightly  oblique  to  the  optical  axis.  Subject's  eye  and  20D  lens  form  a  re- 
fracting system  like  the  objective  of  the  compound  tnicroscope.  The  6phthalm6scope 
lens  plays  the  part  of  the  ocular.     The  image  is  real,  inverted  and  magnified,  but 


Outlines  of  Experimental  Physiology  91 


appears  upright.  B,  size  of  the  aerial  image  is  to  b,  size  of  optic  disc  (1.5  mm.)  as  the 
focal  distance  of  the  20  D  lens  D,  (50  mm.)  is  to  D,  the  distance  from  the  nodal 
point  to  the  retina  (15  mm.).     B:1.5-:50:15. 

(3).  With  the  aid  of  the  condenser  study  the  fundus  of  a  fellow  student's  eye 
with  the  ophthalmoscope,  both  with  the  direct  and  indirect  methods.  State  your  ob- 
servations. 

Expt.    CXXXIV.   Positive  After  Images. 

Rest  the  retina  by  closing  the  eye  a  minute.  Suddenly  look  for  two  seconds  at 
an  electric  light  covered  with  a  white  globe.  Then  close  the  eye.  An  image  like 
the  one  looked  at  will  be  seen.     Try  in  a    dark   room. 

Expt.  CXXXV.  Negative  After  Image  or  Successive  Contrast. 

(1),  Rest  the  retina  and  then  stare  steadily  for  half  a  minute  or  so  at  a  white 
square  or  a  white  cross  on  a  black  ground  To  insure  fixation  of  the 
balls,  make  a  small  mark  in  the  center  of  the  white  paper  and  fix  this  steadily. 
Then  suddenly  slip  a  sheet  of  white  paper  over  the  whole.  A  black  square  or  cross 
will  appear  on  the   white  background. 

(2).  After  looking  at  the  square  or  cross,  close  the  eyes.  Can  you  see  the  nega- 
tive after  image? 

(3).  Stare  intentlj'  at  a  bright  red  square  on  a  black  surface  for  twenty  or  thir- 
ty seconds.  Suddenly  interpose  a  white  surface.  Observe  the  color  of  the  after- 
image. Try  blue,  yellow,  and  other  colors.  In  each  case,  the  negative  after  image 
is  of  the  complementary  color. 

(4).  Try  moving  the  eyes  in  their  sockets  to  see  whether  the  after  image  is  due 
to  a  condition  of  the  brain  or  in  the  eye. 

Expt.     CXXXVI.     Testing  Color  Vision. 

(a).  The  palest  shade  of  green  (neither  yellow  nor  blue-green)  is  selected  as  a 
test.  Select  all  the  other  skeins  of  the  same  color  or  one  or  more  confusion  colors. 
(Those  which  a  color-blind  person  picks  out  according  to  defect.  These  may  be 
grey,  light  red  or  light  purple).  The  fact  that  any  confusion  color  is  picked  out, 
shows  that  he  is  color  blind. 

(b).     Determination  of  the  Kind  and  Degree  of  Color  Blindness. 

The  second  test  is  a  medium  purple.  The  test  is  continued  until  all  of  the  pur- 
ples or  certain  confusion  colors  have  been  selected.  A  person  proving  color  blind 
with  the  first  test,  but  who  selects  purples,  blue  and  violet,  is  completely  red  blind. 
If  he  selects  green  and  gray  with  purple,  he  is  completely  green  blind. 

(c).  Third  test.  Select  a  shade  of  medium  yellowish  red.  The  red  blind 
chooses  with  reds,  greens  and  browns  of  darker  shades.  The  green  blind  chooses 
with  reds,  greens  and  browns  of  lighter  shades, 

Expt.  CXXXVII,     Color  Vision. 

Mixing  White  and  Black.  (1).  Place  on  the  spindle  the  graduated  wheel  and 
then  white  and  black  disc,  so  arranged  as  to  show  a  part  of  each.  Rotate  with 
sufficient  velocity  to  cause  blending.  Note  the  resulting  shade.  All  mixtures  of 
black  and  white  form  grays.  In  other  words,  gray  is  white  of  less  intensity.  Us- 
ing black,  and  white  discs  and  the  speed,  tester,  ascertain  the  number  of  revolutions 
(interruptions)  just  sufficient  to  produce  blending. 


92  Outlines  of  Experimental  Physiology 

(II).  Talbot-Plateau  Law,  etc  (I).  Use  disc  No.  1.  Note  that  the  propor- 
tion of  white  and  black  are  equal  in  all  the  circles  but  differently  distributed. 
Rotate  and  observe  the  greys  produced.     Are  they  alike? 

(2).  Mix  any  two  colors;  using  just  enough  speed  to  insure  a  uniform  color. 
Increase  the  speed.  Does  the  color  produced  depend  on  (1),  the  number  of  interrup- 
tions, (2),  the  manner  of  distribution  of  the  components,  or  (3),  the  proportion  of  the 
components? 

Expt.  CXXXVIII.  Complementary  colors.  See  Bradley,  pp.  50-53.  Place  on 
the  wheel  the  graduated  circle,  the  medium-sized  R,  C,  and  B  wheels  and  the  small 
W  and  N  wheels.  The  problem  is  to  pi'oduce  by  mixing  R,  G,  and  B  the  same  gray 
as  by  mixing  W  and  N.  In  this  case  the  proportions  should  be  about  R,  41>^  ;  B, 
22^2  ;  G,  36,  in  the  larger  disks,  and  W  15;  N  86;  in  the  smaller.  Having  approxi- 
mated the  grays  as  nearly  as  possible,  take  out  the  red  and  combine  the  G  and  B  to 
make  the  full  circle,  but  in  the  same  relative  proportion  as  were  found  above;  (e.  g., 
as  22  Yz  is  to  36).  Rotation  of  this  combination  will  give  the  complementary  of  R. 
It  is  greenish-blue.     Test  this  by  the  negative  after  image  method. 

Expt.  CXXXIX.     The  Skin  as  a  Sense  Organ. 

(1).  Using  a  metal  point  cooled  in  ice  determine  the  distribution  of  cold  points 
on  various  parts  ot  the  skin.  Make  careful  diagrams  of  the  back  of  the  hand, 
palm  and  forearm. 

(2).  Using  a  hot  point,  determine  in  the  same  way  the  distribution  of  the 
wai-m  points.  Make  diagrams  as  in  (1)  of  the  size  so  that  they  may  be  superim- 
posed. Which  points  (cold  or  warm)  are  most  sharply  defined?  Why?  Which  are 
more  numerous?     Have  they  any  relation  to  hairs? 

(3),  Place  a  piece  of  wood  and  a  piece  of  iron  on  ice  until  they  are  thoroughly 
and  equally  chilled  Which  feels  the  colder?  Why?  Repeat,  using  heat  instead 
of  cold.  Test  the  sensation  caused  by  dipping  the  finger  into  water  and  mercury 
at  the  same  temperature. 

(4).  Arrange  two  vessels  of  water  so  that  the  temperature  of  the  water  may  be 
changed  at  will  and  determine  it  accurately  by  means  of  thermometers.  In  these, 
heat  or  cool  two  metal  points  and  by  applying  them  to  the  skin,  determine  the 
smallest  difference  in  teitiperature  which  can  be  appreciated  by  the  skin  of  various 
parts  of  the  body  Is  the  difference  greater  or  less  when  the  points  are  warmer  or 
colder  than  the  skin?     Make  tabulations, 

(5).   Is  there  a  latent  period  in  the  appreciation  of  cold  and  heat?     Which  is    the 

larger? 

(6/.  Hold  one  hand  in  water  at  15°  C  and  the  other  in  water  at  40  OQ.  After 
several   minutes,  plunge  both  hands  into  water  at  25  °  C.     Explain    the    sensation, 

Expt.  CXL.   Hearing. 

(1).  Hold  a  ticking  watch  between  your  teeth,  close  both  ears  and  observe  that 
the  ticking  is  heard  more  plainly.  Why?  Unstop  ohe  ear.  In  which  ear  is  the 
sound  then  the  louder? 

(2).  Hold  a  vibrating  tuning  fork  to  one  ear  until  it  is  no  longer  heard.  Now 
place  it  on  the  incisor  teeth  until  you  no  longer  hear  the  sound;  now  close  both  ears. 
How  about  the  sound  in  each  case?  > 


Outlines  of  Experimental  Physiology  93 

(3).  Find  where  the  ticking  of  a  watch  just  vanishes'as  the  "watch  is  moved 
away;  measure  the  distance  from  the  ear.  Also  find  the  point  where  the  tick  can 
just  be  heard  as  the  watch  is  brought  nearer;  compare  the  two  distances 

(II'.  Direction  of  Sound. 

Blindfold  a  person  and  test  his  sense  of  direction  of  sound. 

Expt.    CXLI.   Taste. 

It  is  well  not  to  smoke  on  the  day  previous  to  performing  these  experiments. 
At  least  the  student  should  not  smoke  on  the  same  day  that  he  performs  his  experi- 
ments. 

It  is  best  in  the  following  experiments  that  two  students  work  together. 
The  experimenter  should  get  his  results  from  the  statements  made  by  the  student 
worked  upon,  who  should  not  be  allowed  to  know  what  solution  he  is  given  to    taste. 

(1).  Let  the  student  experimented  upon,  thoroughl3'  rinse  his  mouth  with  dis- 
tilled water.  Give  about  4  cc.  of  M/200  hydrochloric  acid  What  is  the  taste? 
Give  the  same  amount  of  M/  100  sodium  chloride.  Has  it  a  sour  taste?  What  de- 
termines the  sour  taste  of  HCl?  Give  a  4  cc.  of  M/400  Sulphuric  acid;  of 
M/400  nitric  acid.  What  is  the  taste  of  these?  What  gives  the  sour  taste  to  acids? 
Begin  with  an  M/1000  HCl  solution  and  gradually  increase  the  strength.  Where 
do  you  get  the  first  taste  of  the  H  ions?     Is  the  first  taste  a  sour  one? 

(2).  Taste  an  M/200  sodium  hydrate  solution.  What  is  the  taste?  Has  an 
M/200  NaCl  solution,  a  similar  taste?  Taste  an  M/200  potassium  hj'drate  solu- 
tion. What  determines  an  alkaline  taste?  Find  the  weakest  solution  in  which  you 
can  recognize  the  OH  ions. 

(3).  What  is  the  taste  of  an  M/25  sodium  chloride  solution?  Has  an  M/25 
sodium  acetate  solution  the  same  taste?  What  determines  the  salty  taste  of  sodium 
chloride?  Try  an  M/50  and  stronger  solutions  of  sodium  iodide  and  sodium  brom- 
ide. Have  these  a  salty  taste?  Compare  with  equimolecular  solutions  of  sodium 
acetate.     What  is  the  taste  of  halogen  ions? 

(4;.  Taste.  Dry  the  tongue  thoroughly  and  place  on  the  tip  a  crystal  of  sugar; 
or  on  the  back,  one  of  quinine  sulphate.     Neither  will  be  tasted  until  it  is  dissolved. 

(5).  Apply  with  pointed  non-polarized  electrodes  a  constant  current  to  the 
tongue.     A  distinct  sensation  of  taste  will  be  felt. 

(6).  Determine  in  this  way  the  relative  sensitiveness  to  taste  of  the  various 
parts  of  the  tongue.  Make  a  diagram.  Can  different  sensations  be  obtained  by 
stimulating  different  regions  of  the  tongue?  Where  is  sensation  most  acute?  Re- 
peat with  dilute  acetic  acid.     Also  with  sulphate  of  quinine  and  common  salt. 

(7).  After-tastes,  (a).  Make  a  solution  of  sugar  which  has  no  sweet  taste, 
wash  the  mouth  out  with  salt  water  and  then  test  the  sugar  solution. 

(b).  Wash  the  mouth  with  dilute  sulphuric  acid.  Even  distilled  water  then 
gives  the  sensation  of  sweetness. 

Expt.  CXLII.   Study  of  the  Larynx. 

Draw  a  side  and  longitudinal  view  of  the  human  larynx,  illustrating  the 
glosso-epiglottidean  fold:  lip  and  cushion  of  the  epiglottis,  cartilages  of  Wrisberg 
and  Santorini;  vocal  cord;  ventricular  band;  processus  vocalis;  cricoid  cartilage 
and  arytenoid  commissure. 

Experiment  on  a  living  person. 


M  Outlines  of  Experiraental  Physiology 


(a).  Place  the  person  uprig^ht  iu  a  chair.  A  good  artificial  light  with  a  con- 
dmser  is  plaxied  near  the  side  of  the  subject's  head  a  little  above  the  level  oi  the 
month.  The  observer  seats  himself  opposite  and  close  to  the  patient,  places  the 
large  mirror  on  his  forehead  and  either  looks  through  the  central  hole  in  it  with 
one  eye  or  raises  it  so  that  he  can  just  see  under  itss  lower  edge.  Seated  in  front  of 
the  subject,  the  obser%'er  directs  a  beam  of  light  so  that  the  lips  of  the  patient  are 
brightly  illuminated.  The  subject  is  then  directed  to  incline  his  head  slightly 
backward  to  open  wide  his  mouth  and  to  protude  his  tongue.  Place  a  clean  nap- 
kin over  the  toague  and  have  the  student  hold  it  himself  or  use  the  tongue  depressor 
and  0.2  per  cent  cocaine  spray.  Move  the  head  mirror  until  the  throat  and  uvula  are 
brig^htly  lighted.  Note  the  tonsils  Take  the  small  laryngeal  mirror  in  the  right 
hand  and  warm  it  gentlj-  over  the  lamp  to  prevent  the  condensation  of  moisture  on 
its  surface.  Test  its  temperature  on  the  cheek,  lest  you  burn  the  patient.  Holding 
the  handle  of  the  mirror  as  one  does  a  pen,  rapidly  carry  it  horL&ontall^'  backwards, 
avoiding  contact  with  any  structure  in  the  mouth,  until  its  back  rests  against  the 
base  of  the  uvula.  At  the  same  time  direct  the  light  upon  the  laryngeal  mirror 
when  an  inverted  image  of  the  larynx  will  be  seen  more  or  less  perfectly.  By  mov- 
ing the  laryngeal  mirror,  not  however  pressing  to  much  on  the  uvula  or  continuing 
ibe  observation  for  too  long  a  time  one  may  explore  the  whole  of  the  larynx.  Per- 
haps only  the  posterior  part  of  the  dorsum  of  the  tongue  is  seen  at  first;  if  so, 
slightly  depress  the  handle  of  the  mirror  when  the  curved  fold  of  the  slightly 
yellowish  epiglottis  and  its  cushion  with  the  glosso-epiglottidean  folds  come  into 
view.  In  the  middle  plane  are  the  true  vocal  cords  which  are  pearly  white  and 
shining  and  best  seen  when  a  high  note  is  uttered;  and  between  the  chink  of  the 
glottis.  Above  these  are  the  false  vocal  cords  which  are  red  or  pink,  the  ary-epi- 
glottidean  folds,  with  the  cartilages  of  Wrisberg  on  each  side  furthest  out,  the 
cartilages  of  Santorini  internal  to  this,  and  the  arytenoid  cartilages  near  the 
middle  plane.  Ask  the  patient  to  sing  a  deep  and  then  a  high  note,  or  to  inspire 
feebly  or  deeply  and  observe  the  change  in  the  shape  of  the  glottis.  On 
uttering  a  deep  note,  the  tracheal  rings  may  be  seen. 

N.  B.  What  is  fieen  by  the  observer  in  the  laryngeal  mirror  on  his  right  cor- 
responds to  the  patient's  left  and  vice  versa.  Also  the  lower  part  of  the  mirror 
gives  an  image  of  the  more  posterior  structures,  while  the  anterior  structures  are 
reflected  in  its  upper  part. 

Glosso-epiglottidean  fold,  three  ridges  on  the  pharynx  side  of  the  epiglottis,  like 
thefrenumof  the  tongue,  cushion  of  epiglottis,  thickening  on  larynx  side  of 
epiglottis 

bantorini—Comiculum  laryngis. 
Wri»berg=Cuneiform  cartilage. 

Material;— Cocaine,  cotton,  light,  carbolic,  towel,  cuspidflar. 


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